Ncert – class 9- science – Chapter 8 – Force and Laws of Motion 1 Welcome to your Ncert - class 9- science - Chapter 8 – Force and Laws of Motion 1 1. How much force acts on body whose momentum is constant (i.e. = constant)? p/2t None 2p/t Zero None 2. Statement A: Gravitational force is the weakest force in nature Statement B: Electrostatic force is the example of non – contact force Which of the above two statement is true? statement B statement A neither statement A nor B both the statement a and b None 3. What is the action reaction pair when we walk on the floor? Air resistance, force applied by road on your feet Air resistance, muscular force None of these Your feet exerts force on road, road reverts equal force back, None 4. Match the following with correct response. (1) Cause of acceleration (2) Quantitative measure of inertia (3) powder applied on carom board (4) Tyres of vehicles made Rough (A) Mass (B) Increases friction (C) Decreases friction (D) Force 1-B, 2-D, 3-A, 4-C 1-D, 2-A, 3-C, 4-B 1-A, 2-C, 3-B, 4-D 1-C, 2-B, 3-D, 4-A None 5. What happens when some children try to push a box on a rough floor? The box will move regardless of the force given The box does not move with a small force The box moves with a little force None of these None 6. When a toothpaste tube is squeezed, it's shape changes. The force responsible for this is an example of _______. Balanced force Tangential force Centripetal force Unbalanced force None 7. Choose the correct statement from the following:Weightlessness of an astronaut moving in a satellite is a situation of Free fall Zero mass No gravity Zero g None 8. Which of the following uses the principle of conservation of momentum? Ballon moves upwards when burst or when air is expelled out of it Gun recoils after firing Motion of rockets and jet engines All of these None 9. A truck is moving on a frictionless surface with uniform velocity of 10ms −1 . A leak occurs in the water tank of the truck at the rate of 2kg −1 What is the speed of truck after 50 s, if the mass of truck is 100kg and mass of water in the truck initially was 100kg? 5ms −1 10ms −1 None of these 20ms −1 None 10. An object maintains its motion under the continuous application of ________force A weak An unbalanced A balanced A strong None 11. Principle of rocket is based on Newton's ......... law of motion. First Third Second None None 12. Ayush hits a cricket ball which than rolls of a level ground after covering a short distance, the ball comes to rest. The ball slows to a stop because Ayush did not hit the ball hard enough Velocity is proportional to the force exerted on the ball. There is a force on the ball opposing the motion There is no unbalanced force on the ball so the ball would want to come to rest., None 13. Match the following with correct response. (1) Action and reaction (2) Magnitude of force (3) Momentum (4) Resultant of balanced force (A) No acceleration (B) Newton’s second law (C) Act on different objects (D) Scalar quantity 1-B, 2-D, 3-A, 4-C 1-D, 2-A, 3-C, 4-B 1-A, 2-C, 3-B, 4-D 1-C, 2-B, 3-D, 4-A None 14. Match the following with correct response. (1) Cart pulled by a horse (2) Backward jerk (3) Sole of shoe worn out (4) Recoiling of gun (A) Friction (B) Newton’s III law of motion (C) Law of conservation of momentum (D) Law of inertia 1-A, 2-C, 3-B, 4-D 1-C, 2-B, 3-D, 4-A 1-D, 2-A, 3-C, 4-B 1-B, 2-D, 3-A, 4-C None 15. What is the direction of the unbalanced force acting on a body which is accelerating in a straight line? In the direction opposite to the motion of the body. In the direction of motion of the body. In the direction perpendicular to the motion of the body. None of these. None 16. A bullet weighing 50 gram leaves the gun with a velocity of 30m/s.the ratio of their momentum is: 1:2 2:1 1:3 1:1 None 17. What is the product of force and the time for which force acts known as? Impulse of force Momentum Inertia Acceleration None 18. Identify the incorrect statement. The tension of a string always pulls a body. Frictional force always acts parallel to the surface of contact. The weight of a body always acts towards the centre of the Earth. The spring force always pushes a body. None 19. A hockey player pushes the ball on the ground. Why does the ball come to rest after travelling a certain distance? No unbalanced force acts on the ball. The opposing force of friction acts on the ball. The player stops pushing the ball. The ball moves only when pushes. None 20. If an object experiences a net zero unbalanced force, then the body cannot remain at rest can be accelerated moves with a constant velocity will always remain at rest None Time's up Please Share This Share this content Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Leave a Reply Cancel replyCommentEnter your name or username to commentEnter your email address to commentEnter your website URL (optional) Save my name, email, and website in this browser for the next time I comment.
