C9 2. Force
1. What is force? Write its SI unit.
Ans: Force is an external agent that changes or tries to change the state of rest or motion of and object. It can also change the direction of moving bodies, can change the speed of a body and can change the shape and size of an object.
Its SI unit is Newton(N).
2. What are the effects of force?
Ans: The effects of force are:
i. It can change the state of rest or motion of an object.
ii. It can change the direction of moving bodies.
iii. It can change the shape and size of an object.
iv. It can change the speed of a moving body.
3. Define balanced force and unbalanced force with examples.
Ans: Balanced forces are equal in magnitude and opposite in direction. These force can not cause a change in motion. In this case resultant force is always zero. E.g: equal forces applied in opposite direction in tug or war, a book kept at rest on a table etc.
Unbalanced forces are not equal in magnitude and are applied in the opposite direction or sometimes in the same direction. They can cause a change in motion. In this case resultant force is never zero. E.g: a book sliding on an inclined plane, ball rolls in one direction when kicked etc.
4. What is meant by 1N force?
Ans: 1N force is defined as the amount of force applied to a mass of 1 Kg which moves with an acceleration 1 m/s2 in the direction of force.
5. Define Rest and motion with example.
Ans: A body is said to be in rest if it does not change it position with respect to its surrounding objects.
A body is said to be in motion if it changes it position with respect to its surrounding objects.
6. Define uniform motion and write one example of it.
Ans: If a body travels equal distance in equal interval of time the motion of an object is called uniform motion. The motion of heavenly bodies around the sun is an example of uniform motion.
7. What do you mean by vector and scalar quantities? Give two examples of each.
Ans: Vector quantity is the physical quantity which has both magnitude and direction. E.g: force, acceleration etc.
Scalar quantity is the physical quantity which has only magnitude but no direction. E.g: speed, Temperature, density etc.
8. Define distance and displacement with example.
Ans: The total length of path between two points is called distance. It is a scalar quantity.
The shortest length of path between two points is called displacement. It is a vector quantity.
9. What do you mean by speed, uniform speed, velocity, uniform velocity? Give examples of each.
Ans: Speed of an objects is defined as the distance traveled by a body per unit time in any direction. It is a scalar quantity.
If a body travels equal distance in equal interval of time the motion of that object is called uniform speed.
10. Define average speed and average velocity.
Ans: Average speed is defined as the total distance traveled by a body in any direction per total time taken.
Average velocity is defined as the total distance traveled by a body in a particular direction per total time taken.
11. Is velocity a vector or scalar quantity? Give a reason to your answer.
Ans: Actually Velocity is a vector quantity as both magnitude and direction are required to express it.
12. Write down the definition of acceleration and retardation.
Ans: Acceleration is defined as the rate of change of velocity with time.The negative acceleration is known as retardation.
13. What is uniform acceleration?
Ans: Uniform acceleration is a type of motion in which the velocity of an object changes by an equal amount in every equal time period.
14. What do you mean by inertia? On what factor does the inertia of a body depend?
Ans: Inertia is the resistance of any physical object to any change in its velocity. The inertia of a body depends on mass.
15. Define inertia of rest and inertia of motion.
Ans: Inertia of rest is the property of a body by virtue of which it tends to remain in the state of rest unless an external force is applied on it.
Inertia of motion is the property of a body by virtue of which it tends to remain in the state of uniform motion unless external force is applied on it.
16. What inertia is present in a stretched rubber?
Ans:The inertia of rest is present in a stretched rubber.
17. Define mass and weight.
Ans: Mass is the quantity of matter contained a body. It is measured in kg.
Weight is the measurement of force of gravity acts on a body. Its SI unit is N.
18. What is the relation between mass and inertia of an object?
Ans: The inertia of massive object has more inertia and less mass object has less inertia.
19. State Newton’s first law of motion. Newton’s first law of motion is also called the law of inertia, explain.
Ans: Newton's first law of motion states that "every object in the universe continues in the state of rest or uniform motion in a straight line unless an external force acts on it.
Newton’s first law of motion is also called the law of inertia because the greater the inertia of a body, the larger force is required to bring the change in its state of rest or uniform motion, as inertia is the property of a body due to which it resists the change in its state of rest or state of uniform motion.
20. State Newton’s second law of motion.
Ans: Newton’s second law of motion state that "the acceleration of an object as produced by a net force is directly proportional the net force, in the same direction as the net force, and inversely proportional to the mass of the object."
21. Prove that F = ma.
Ans: Let us consider a body of mass ‘m’ is moving with an acceleration ‘a’ with a force ‘F’ in the direction of force. According to Newton’s second law of motion,
Ans: Newton’s third law of motion states that "To every action there is an equal and opposite reaction".
23. Explain the action of a rocket on the basis of Newton’s law of motion.
Ans: In a rocket, the burnt gases are exhausted out (forcefully thrown out) in vertically downward direction with a large force (action). These gases exert an equal and opposite force on the rocket in upward direction (reaction) due to which the rocket is pushed in upward direction.
24. Derive the relation v = u + at.
Ans: Let us consider a body is moving with an initial velocity 'u' and after travelling a distance 'd' for time 't' its velocity reaches to 'v' with an acceleration 'a'. By the definition of acceleration,
1. What is force? Write its SI unit.
Ans: Force is an external agent that changes or tries to change the state of rest or motion of and object. It can also change the direction of moving bodies, can change the speed of a body and can change the shape and size of an object.
Its SI unit is Newton(N).
2. What are the effects of force?
Ans: The effects of force are:
i. It can change the state of rest or motion of an object.
ii. It can change the direction of moving bodies.
iii. It can change the shape and size of an object.
iv. It can change the speed of a moving body.
3. Define balanced force and unbalanced force with examples.
Ans: Balanced forces are equal in magnitude and opposite in direction. These force can not cause a change in motion. In this case resultant force is always zero. E.g: equal forces applied in opposite direction in tug or war, a book kept at rest on a table etc.
Unbalanced forces are not equal in magnitude and are applied in the opposite direction or sometimes in the same direction. They can cause a change in motion. In this case resultant force is never zero. E.g: a book sliding on an inclined plane, ball rolls in one direction when kicked etc.
4. What is meant by 1N force?
Ans: 1N force is defined as the amount of force applied to a mass of 1 Kg which moves with an acceleration 1 m/s2 in the direction of force.
5. Define Rest and motion with example.
Ans: A body is said to be in rest if it does not change it position with respect to its surrounding objects.
A body is said to be in motion if it changes it position with respect to its surrounding objects.
6. Define uniform motion and write one example of it.
Ans: If a body travels equal distance in equal interval of time the motion of an object is called uniform motion. The motion of heavenly bodies around the sun is an example of uniform motion.
7. What do you mean by vector and scalar quantities? Give two examples of each.
Ans: Vector quantity is the physical quantity which has both magnitude and direction. E.g: force, acceleration etc.
Scalar quantity is the physical quantity which has only magnitude but no direction. E.g: speed, Temperature, density etc.
8. Define distance and displacement with example.
Ans: The total length of path between two points is called distance. It is a scalar quantity.
The shortest length of path between two points is called displacement. It is a vector quantity.
9. What do you mean by speed, uniform speed, velocity, uniform velocity? Give examples of each.
Ans: Speed of an objects is defined as the distance traveled by a body per unit time in any direction. It is a scalar quantity.
If a body travels equal distance in equal interval of time the motion of that object is called uniform speed.
10. Define average speed and average velocity.
Ans: Average speed is defined as the total distance traveled by a body in any direction per total time taken.
Average velocity is defined as the total distance traveled by a body in a particular direction per total time taken.
11. Is velocity a vector or scalar quantity? Give a reason to your answer.
Ans: Actually Velocity is a vector quantity as both magnitude and direction are required to express it.
12. Write down the definition of acceleration and retardation.
Ans: Acceleration is defined as the rate of change of velocity with time.The negative acceleration is known as retardation.
13. What is uniform acceleration?
Ans: Uniform acceleration is a type of motion in which the velocity of an object changes by an equal amount in every equal time period.
14. What do you mean by inertia? On what factor does the inertia of a body depend?
Ans: Inertia is the resistance of any physical object to any change in its velocity. The inertia of a body depends on mass.
15. Define inertia of rest and inertia of motion.
Ans: Inertia of rest is the property of a body by virtue of which it tends to remain in the state of rest unless an external force is applied on it.
Inertia of motion is the property of a body by virtue of which it tends to remain in the state of uniform motion unless external force is applied on it.
16. What inertia is present in a stretched rubber?
Ans:The inertia of rest is present in a stretched rubber.
17. Define mass and weight.
Ans: Mass is the quantity of matter contained a body. It is measured in kg.
Weight is the measurement of force of gravity acts on a body. Its SI unit is N.
18. What is the relation between mass and inertia of an object?
Ans: The inertia of massive object has more inertia and less mass object has less inertia.
19. State Newton’s first law of motion. Newton’s first law of motion is also called the law of inertia, explain.
Ans: Newton's first law of motion states that "every object in the universe continues in the state of rest or uniform motion in a straight line unless an external force acts on it.
Newton’s first law of motion is also called the law of inertia because the greater the inertia of a body, the larger force is required to bring the change in its state of rest or uniform motion, as inertia is the property of a body due to which it resists the change in its state of rest or state of uniform motion.
20. State Newton’s second law of motion.
Ans: Newton’s second law of motion state that "the acceleration of an object as produced by a net force is directly proportional the net force, in the same direction as the net force, and inversely proportional to the mass of the object."
21. Prove that F = ma.
Ans: Let us consider a body of mass ‘m’ is moving with an acceleration ‘a’ with a force ‘F’ in the direction of force. According to Newton’s second law of motion,
Acceleration produced on a body is directly proportional to
the force applied and inversely proportional to the mass of the body. So,
$a\text{ }\alpha \text{ F}................\text{i}$
$a\text{ }\alpha \frac{1}{m}................\text{ii}$
Combining equation (i) and (ii) we get,
\[a\text{ }\alpha \frac{F}{m}................\text{iii}\]
\[F\alpha \text{ ma}...............\text{iv}\]
When we remove the proportionality sign
of equation iv we get,
\[F=\text{ kma}...............\text{v}\]
Where k is the proportionality constant.
The value of k depends on the system of unit. Its value is one in SI unit. The
equation (v) becomes,
\[F=\text{ ma}...............\text{vi}\]
Ans: Newton’s third law of motion states that "To every action there is an equal and opposite reaction".
23. Explain the action of a rocket on the basis of Newton’s law of motion.
Ans: In a rocket, the burnt gases are exhausted out (forcefully thrown out) in vertically downward direction with a large force (action). These gases exert an equal and opposite force on the rocket in upward direction (reaction) due to which the rocket is pushed in upward direction.
24. Derive the relation v = u + at.
Ans: Let us consider a body is moving with an initial velocity 'u' and after travelling a distance 'd' for time 't' its velocity reaches to 'v' with an acceleration 'a'. By the definition of acceleration,
\[acceleration\text{ = }\frac{\text{Final velocity - Inital
velocity}}{Time}\]
\[a\text{ = }\frac{v-u}{t}................i\]
\[\text{or, v = u + at}...............ii\]
25. Prove that : S = ut + ½ at2
Let us consider a body is moving with an initial velocity 'u' and after travelling a distance 'd' for time 't' its velocity reaches to 'v' with an acceleration 'a'. By the definition of acceleration,
\[acceleration\text{ = }\frac{\text{Final velocity - Inital velocity}}{Time}\]
\[a\text{ = }\frac{v-u}{t}................i\]
\[\text{or, v = u + at}...............ii\]
Suppose distance travelled by the body in time ‘t’ is equal to ‘s’ then,
Distance travelled = Average velocity × time taken
But,
\[\text{Average velocity = }\frac{\text{u + v}}{2}\]
So, Distance travelled is
\[\text{S = }\frac{\text{u + v}}{\text{2}}\text{ }\!\!\times\!\!\text{ t}............\text{iii}\]
Substituting the value of ‘v’ from equation (ii) to equation (iii), we get
\[\text{or, S = }\frac{\text{u +(u+at) }}{2}\text{ }\!\!\times\!\!\text{ t}\]
\[\text{or, S = }\left( \frac{\text{2u+at}}{\text{2}} \right)\text{ }\!\!\times\!\!\text{ t}\]
\[\text{or, S = }\left( \frac{\text{2u}}{\text{2}} \right)\text{t+}\left( \frac{\text{at}}{\text{2}} \right)\text{t}\]
Ans:
Let us consider a body is moving with an initial velocity 'u' and after travelling a distance 'd' for time 't' its velocity reaches to 'v' with an acceleration 'a'. By the definition of acceleration,
\[acceleration\text{ = }\frac{\text{Final velocity - Inital velocity}}{Time}\]
\[a\text{ = }\frac{v-u}{t}................i\]
\[\text{or, v = u + at}...............ii\]
Suppose distance travelled by the body in time ‘t’ is equal to ‘s’ then,
Distance travelled = Average velocity × time taken
But,
\[\text{Average velocity = }\frac{\text{u + v}}{2}\]
So, Distance travelled is
\[\text{S = }\frac{\text{u + v}}{\text{2}}\text{ }\!\!\times\!\!\text{ t}............\text{iii}\]
\[\text{or, S = }\left( \frac{\text{u+v}}{\text{2}}
\right)\text{ }\!\!\times\!\!\text{ }\left( \frac{\text{v-u}}{\text{a}} \right)\text{ }\left[ \because \text{t = }\frac{v-u}{a}
\right]\]
\[\text{or, S = }\frac{\text{(v+u)(v-u)}}{\text{2a}}\]
\[\text{or, S
=}\frac{{{\text{v}}^{\text{2}}}\text{-}{{\text{u}}^{\text{2}}}}{\text{2a}}\]
\[\text{or, }{{\text{v}}^{\text{2}}}\text{- }{{\text{u}}^{\text{2}}}\text{ = 2as }............\text{v}\]
27. Define momentum with its SI unit.
Ans: Momentum is the quantity of motion contained in a body. Its SI unit is kg m/s.
28. On what factors does momentum of a body depends on?
Ans: Velocity of the moving body and mass are the factors in which momentum of a body depends on.
29. Write the conditions in which acceleration becomes zero.
Ans: Acceleration becomes zero if the velocity of the body is constant as acceleration is the rate of change in velocity per unit time.
30 Give reasons:
a. The weight of a body differs from place to place but inertia of the body remains the same.
Ans: Weight of a body depends up on the acceleration due to gravity of a planet or heavenly body while mass is the constant quantity which does not depend upon gravity of a planet. Inertia is the inability of a body to change its state of rest or motion of the object which depends on the mass of the body. So, weight of the body differ from place to place but inertia of the body remains the same.
b. A truck and a car are moving with the same speed but the truck takes longer time to stop than that taken by a car.
Ans: Inertia of a body depends on the mass of the body. The truck has more mass than that of car. So, the truck has more inertia than that of car when they are in motion due to which the truck takes longer time to stop than car.
c. More force is required to stop a moving truck than to stop a moving car.
Ans: Inertia of a body depends on the mass of the body. The truck has more mass than that of car. So, the truck has more inertia than that of car when they are in motion. We have to apply more force to the truck to bring it into rest as it has more inertia of motion because of its more mass than that of car.
d. Distance is called scalar quantity but displacement is a vector quantity.
Ans: Distance is the total length of path which has not the fixed direction but displacement is the shortest distance between two points which is always a straight line. So, scalar can be described by magnitude only but vector is described by both magnitude and direction. The quantity with magnitude and direction is called vector and the quantity which has magnitude is called scalar. Therefore, displacement is vector quantity and distance is scalar quantity.
e. Newton's first law of motion is also called the the 'law of inertia’.
Ans: According to Newton's first law of motion a body remains in rest or move uniformly in straight line until an external force is applied. Similarly a body can not change its state of rest or motion by itself. The tendency of of a body to remain in its state of rest or motion is called inertia. So Newton's first law of motion is also called the law of inertia.
f. While catching a cricket ball a cricket player lowers his hand backwards.
Ans: While catching a cricket ball a cricket player lowers his hand backwards to reduce the damage caused by the impact of the ball with his hand. As we know that force is inversely proportional to the time of impact, while lowering his hand backward time of flight of the ball becomes more and reduces the force in his hand and hearts less.
g. While lifting water from the well if the rope breaks, a person falls backward.
Ans: According to Newton's third law of motion while lifting water from the well a person applies the force to lift the bucket as an action. Similarly, the bucket of water in a well exerts equal and opposite force as a reaction. When the rope breaks, that reaction force does not exist anymore and due to law of inertia, the person tends to keep pulling away from the well and falls in the backward direction when the reaction force disappears.
h. Dust particles get separated when carpet is beaten by a stick.
Ans: When we beat the carpet by a stick then the carpet sets in motion but the dust particles continue to be in state of rest. Due to inertia of rest, the dust particles get separated from the carpet.
i. Passengers fall forward when brake is suddenly applied in a bus.
Ans: When a bus is moving , the passengers inside the bus are also in motion with the bus. If the bus is suddenly stopped by applying brake, the lower part of the body of passengers sets at rest but upper part of the body tends to remain in motion with the bus. Due to inertia of motion, passengers fall forward.
j. An athlete runs some distance before taking a long jump.
Ans: An athlete runs some distance before taking a long jump to gains the inertia of motion. This helps the athlete to have a longer jump.
k. Passengers of a bus fall backward when a bus suddenly starts to move.
Ans: When a bus is at rest, the passengers are also at rest. When the bus is suddenly starts to move, the lower part of the body of passengers comes into motion with bus but the upper part of the body tends to be at rest. Due to inertia of rest, passengers fall backward.
l. Mango fruits fall from a tree when the tree is broken.
Ans: Before shaking the branches, both the branches and the mango are at rest. After shaking, branches come in motion but mango still tends to be at rest. Due to inertia of rest, mango fall down.
m. A coin placed on the top of cardboard placed above the glass tumbler falls into it, if cardboard is sudden pulled on one side.
Ans: At first, both the cardboard and coin are at rest. When the cardboard is pulled or pushed suddenly with a jerk, the cardboard sets in motion but coin tends to be in rest. Due to inertia of rest the coin falls into the glass tumbler when cardboard come in motion suddenly.
n. It is dangerous to jump out from the moving vehicles.
Ans: It is dangerous to jump out from the moving vehicles because when we come in contact with the ground, out feet come to rest, but due to inertia of motion the upper part of our body continues to move. So, we may fall down in the direction of motion of the bus and get injured.
o. A moving fan continues to move after switch off.
Ans: A switched on fain gains inertia of motion when in motion and try to remain in motion even if the switch is off. Hence, fan continues to rotate even if switched off.
p. It is easier to drag a stone than to kick it.
Ans: A stone is in rest state and tends to remain in rest when we suddenly kick due to inertia of rest and we kick the stone, the stone exerts an equal and opposite force on the leg which hurts us but it is easier to drag it. While dragging a stone we can apply full force with the help of frictional force on the foot with ground.
q. A person falling on the cemented floor is injured more than person falling on sandy floor.
Ans: We know that cemented floor is harder than that of sandy floor so time of impact is less in cemented floor which provides the reaction force to the person falling on it, as force is inversely proportional to time of impact. Hence, person gets hurt while falling on the cemented floor than the sandy floor.
r. A balloon moves backward when air rushes out of it.
Ans: When a balloon filled air is released the air inside it rushes out in forward (action) and the balloon moves backward (reaction) according to Newton's third law of motioin.
s. It is difficult to walk on sand surface.
Ans:
t. We slip on a muddy road.
Ans:
u. Birds can fly by flipping their wings.
Ans:
v. A swimmer pushes water backward.
Ans:
w. A gun recoils when a bullet is fired from it.
Ans:
Ans: When we beat the carpet by a stick then the carpet sets in motion but the dust particles continue to be in state of rest. Due to inertia of rest, the dust particles get separated from the carpet.
i. Passengers fall forward when brake is suddenly applied in a bus.
Ans: When a bus is moving , the passengers inside the bus are also in motion with the bus. If the bus is suddenly stopped by applying brake, the lower part of the body of passengers sets at rest but upper part of the body tends to remain in motion with the bus. Due to inertia of motion, passengers fall forward.
j. An athlete runs some distance before taking a long jump.
Ans: An athlete runs some distance before taking a long jump to gains the inertia of motion. This helps the athlete to have a longer jump.
k. Passengers of a bus fall backward when a bus suddenly starts to move.
Ans: When a bus is at rest, the passengers are also at rest. When the bus is suddenly starts to move, the lower part of the body of passengers comes into motion with bus but the upper part of the body tends to be at rest. Due to inertia of rest, passengers fall backward.
l. Mango fruits fall from a tree when the tree is broken.
Ans: Before shaking the branches, both the branches and the mango are at rest. After shaking, branches come in motion but mango still tends to be at rest. Due to inertia of rest, mango fall down.
m. A coin placed on the top of cardboard placed above the glass tumbler falls into it, if cardboard is sudden pulled on one side.
Ans: At first, both the cardboard and coin are at rest. When the cardboard is pulled or pushed suddenly with a jerk, the cardboard sets in motion but coin tends to be in rest. Due to inertia of rest the coin falls into the glass tumbler when cardboard come in motion suddenly.
n. It is dangerous to jump out from the moving vehicles.
Ans: It is dangerous to jump out from the moving vehicles because when we come in contact with the ground, out feet come to rest, but due to inertia of motion the upper part of our body continues to move. So, we may fall down in the direction of motion of the bus and get injured.
o. A moving fan continues to move after switch off.
Ans: A switched on fain gains inertia of motion when in motion and try to remain in motion even if the switch is off. Hence, fan continues to rotate even if switched off.
p. It is easier to drag a stone than to kick it.
Ans: A stone is in rest state and tends to remain in rest when we suddenly kick due to inertia of rest and we kick the stone, the stone exerts an equal and opposite force on the leg which hurts us but it is easier to drag it. While dragging a stone we can apply full force with the help of frictional force on the foot with ground.
q. A person falling on the cemented floor is injured more than person falling on sandy floor.
Ans: We know that cemented floor is harder than that of sandy floor so time of impact is less in cemented floor which provides the reaction force to the person falling on it, as force is inversely proportional to time of impact. Hence, person gets hurt while falling on the cemented floor than the sandy floor.
r. A balloon moves backward when air rushes out of it.
Ans: When a balloon filled air is released the air inside it rushes out in forward (action) and the balloon moves backward (reaction) according to Newton's third law of motioin.
s. It is difficult to walk on sand surface.
Ans:
t. We slip on a muddy road.
Ans:
u. Birds can fly by flipping their wings.
Ans:
v. A swimmer pushes water backward.
Ans:
w. A gun recoils when a bullet is fired from it.
Ans:
Posts
Q.no.8 Roshan Acharya:Distance is a scalar quantity that refers to "how much ground an object has covered" during its motion and Displacement is a vector quantity that refers to "how far out of place an object is"; it is the object's overall change in position.
ReplyDeleteQ.no.6.Namrata Tamang: The motion where the velocity of the body travelling in a straight line remains constant as it covers equal distances in the equal intervals of time is called uniform motion. Eg: movement of hands of a watch.
ReplyDeleteQ.no.10 Roshan Acharya : The average speed of an object is defined as the distance traveled divided by the time elapsed andvelocity can be defined as the displacement divided by the time.
ReplyDeleteQ.no.13 Roshan Acharya :Uniform acceleration is a type of motion in which the velocity of an object changes by an equal amount in every equal time period.
ReplyDeleteQ.no.17 Roshan Acharya : Mass is a measurement of the amount of matter something contains and Weight is the measurement of the pull of gravity on an object.
ReplyDeleteQ.no.11. Namrata Tamang: Actually Velocity is a vector quantity as both magnitude and direction are required to express it.
ReplyDeleteQ.no.20 Roshan Acharya: Newton’s second law of motion state that the acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
ReplyDeleteQ.no.20 Roshika Thapa:Newtons second law of motion states that"acceleration produced on a body is directly proportional to the force applied and inversely proportional to its mass."
ReplyDeleteQ.no.22 Roshan Acharya: Newton’s third law of motion states that for every action (force) in nature there is an equal and opposite reaction.
ReplyDeleteQ.no.14.Namrata Tamang:Inertia is the resistance of any physical object to any change in its velocity. The inertia of a body depends on mass.
ReplyDeleteQ.no.27 Roshika Thapa:Momentum is the quantity of motion contained in a body. Its SI unit is kg m/s.
ReplyDeleteQ.no.12(Shreya Poudel)ans:Acceleration is defined as the rate of change of velocity with time.
ReplyDeleteThe negative acceleration is known as retardation.
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DeleteQ.no.7 Roshika Thapa:The quantities which have both direction and magnitude are called vector quantities.Examples:displacement, velocity,acceleration etc.The quantities which have only magnitude are called scalar quantities.Examples:speed,distance travelled,etc.
ReplyDeleteKeep on writhing your answers.
DeleteQ.no.29(Shreya Poudel)ans:Acceleration becomes zero if the velocity of the body is constant as acceleration is the change in velocity.
ReplyDelete