FORCE AND LAWS OF MOTION

1	Inertia of a body is quantitative measure of Its: (a) velocity (b) mass (c) acceleration (d) force	1
2	Which of the following has the largest inertia? (a) Needle (b) water bottle (c) Our body (d) pen	1
3	Newton's second law of motion gives us a measure of: (a) force (b) mass (c) Inertia (d) acceleration	1
4	An object will continue to accelerate until the: (a) velocity changes direction (b) resultant force on it is Increased continuously (c) resultant force begins to decrease (d) resultant force on It Is zero	1
5	A passenger in a moving bus tosses a coin which falls behind him. It means that, motion of the bus is: (a) uniform (b) retarded (c) accelerated (d) along circular motion	1
6	A body, whose momentum is constant, must have constant: (a) force (b) acceleration (c) velocity (d) All of these	1
7	Force required in accelerating a 3 kg mass at 5 m/s² and a 4 kg mass at 4 m/s², will be: (a) zero in both the cases (b) greater for 3 kg mass at 5 m/s² (c) same in both the cases (d) greater for 4 kg mass at 4 m/s²	1
8	According to the third law of motion, action and reaction: (a) always act on the same body (b) always act on different bodies in opposite directions (c) have same magnitude and directions (d) act on either body at normal to each other	1
9	A cannon after firing recoils due to: (a) conservation of energy (b) backward thrust of gases produced (c) Newton's third law of motion (d) Newton's first law of motion	1
10	A man Is standing on a boat in still water. If he walks towards the shore, the boat will: (a) move away from the shore (b) remain stationary (c) move towards the shore (d) sink	1

ASSERTION AND REASON QUESTIONS

(a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

(b) Both Assertion (A) and Reason (R) are true and Reason (R) is not the correct explanation of the Assertion (A).

(c) Assertion (A) is true, and Reason (R) is false.

(d) Assertion (A) is false, and Reason (R) True.

11	Assertion (A): Balanced forces do not change the state of rest or of motion of an object. Reason (R): If a number of forces acting on a body produce an acceleration in the body, then the forces acting are called unbalanced forces.	1
12	Assertion (A): An object maintains its motion under the continuous application of an unbalanced force. Reason (R): The change in the direction of motion would continue as long as this unbalanced force is applied.	1
13	Assertion (A): Newton's second law of motion gives the measurement of force. Reason (R): According to Newton's second law of motion, force is directly proportional to the rate of change of momentum.	1
14	Assertion (A): When a bullet is fired from a gun, the force sending the bullet forward Is equal to the force sending the gun backward. Reason (R): Every action has an equal and opposite reaction.	1

VERY SHORT ANSWER QUESTIONS

15	Apart from changing the magnitude of velocity of an object or changing the direction of motion of an object, what other changes can force bring on an object?	2
16	You are given a heavy object and a light object. Which object will have more inertia?	2
17	Define one Newton force.	2
18	Name the force which is responsible for change in position or state of an object.	2
19	Explain why is it difficult for a fireman to hold a hose, which ejects large amount of water at a high velocity?	2

SHORT ANSWER TYPE QUESTIONS

20	Two balls A and B of masses'm'and'2m'are in motion with velocities '2v' and 'v' respectively. Compare: (I) their inertia, (ii) their momentum, and (iii) the force needed to stop them in the same time.	3
21	A hammer of mass 500 g moving at 50 m/s strikes a nail. The nail stops the hammer in a very short time of 0.01 s. What is the force of the nail on the hammer?	3
22	Explain why some of the leaves may get detached from a tree if we vigorously shake its branch.	3
23	An automobile vehicle has a mass of 1500 kg. What must be the force between the vehicle and road if the vehicle is to be stopped with a negative acceleration of 1.7 m s^-2?	3
24	An object of mass 100 kg is accelerated uniformly from a velocity of 5 m/s to 8 m/s in 6 s. Calculate the initial and final momentum of the object. Also, find the magnitude of the force exerted on the object.	3
25	Why do you fall in the forward direction when a moving bus brakes to a stop and fall backwards when it accelerates from rest?	3
26	Define SI unit of force. A force of 2 N acting on a body changes its velocity uniformly from 2 m/s to 5 m/s in 10 s. Calculate the mass of the body.	3

LONG ANSWER TYPE QUESTIONS

27	A motorcar of mass 1200 kg is moving along a straight line with a uniform velocity of 90 km/h. Its velocity is slowed down to 18 km/h in 4 s by an unbalanced external force. Calculate the acceleration and change in momentum. Also, calculate the magnitude of the force required.	5
28	A 8000 kg engine pulls a train of 5 wagons, each of 2000 kg along a horizontal track. If the engine exerts a force of 40000 N and the track offer a friction force of 5000 N, then calculate (i) the net accelerating force, (ii) the acceleration of the train and (iii) the force of wagon 1 on wagon 2.	5
29	Explain the following: (i) Why do we jerk wet clothes before spreading them on line? (ii) Why fruits fall off the branches in strong wind? (iii) Why a pillion rider falls forward, when the driver of a two wheeler suddenly applies brakes? (iv) How a karate player can break a pile of tiles with a single blow of his hand? (v) A greater force is required to impart a greater velocity to an object.	5
30	Derive the unit of force using the second law of motion. A force of 5 N produces an acceleration of 8 m s^-2 on a mass m, and an acceleration of 24 m s^-2 on a mass m₂. What acceleration would the same force provide if both the masses are tied together?	5
31	Explain the following: (i) Why are the wheels of vehicle provided with mud guards? (ii) Why does a boat tend to leave the shore, when passengers are alighting from it? How does boatman overcome the above difficulty? (iii) Why does a gun recoil, when fixed? (iv) How do the rockets operate in space?	5
32	Give statement of Newton's second law of motion. Deduce a mathematical formulation for it. Using above derived expression. Calculate the force exerted by a nail on the hammer of mass 500g moving at 5.0 m/s striking it, consider that the nail stops the hammer in a short time of 0.01 s.	5
33	(a) State the third law of motion. (b)Which of the following has more inertia? (I) A rubber ball and a stone of same size (ii) A bicycle and a train (iii) A five-rupee coin and a one-rupee coin Give reasons for your answer.	5

CASE BASED STUDY QUESTIONS

34	Read the passage carefully and answer the passage carefully. When a bus suddenly starts moving, passengers tend to fall backward. When the bus suddenly stops, passengers fall forward. 1. Name the law of motion which explains this situation. 2. Why do passengers fall backward when the bus starts suddenly? 3. Why do passengers fall forward when the bus suddenly stops? 4. State the property of matter responsible for this observation. 5. Give one more real-life example of this law.	4
35	Read the passage carefully and answer the passage carefully. Two carts of masses 2 kg and 3 kg are moving towards each other with speeds of 4 m/s and 2 m/s, respectively. They collide and after collision move together. 1. Which law of motion is used to solve this problem? 2. Write the total momentum before collision. 3. Write the total momentum after collision. 4. Calculate their common velocity after collision. 5. State the principle of conservation of momentum.	4
36	Read the passage carefully and answer the passage carefully. A car of mass 1000 kg is moving with a velocity of 20 m/s on a highway. The driver suddenly applies brakes and the car comes to rest in 5 seconds. 1. Which law of motion explains why the car continues moving forward even after brakes are applied? 2. Calculate the acceleration produced in the car. 3. Find the force exerted by the brakes to stop the car. 4. If the driver was not wearing a seatbelt, what could happen? Which law justifies it?	4
37	Read the passage carefully and answer the passage carefully. A rocket of mass 5000 kg expels gases at a velocity of 800 m/s. If the rate of ejection of gases is 10 kg/s, the rocket moves upward. 1. Which law of motion is responsible for the upward motion of the rocket? 2. Calculate the force acting on the rocket due to ejection of gases. 3. If no external force acted on the rocket, what would happen according to Newton’s first law? 4. State the action-reaction forces in this case.	4