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. 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-C, 2-B, 3-D, 4-A 1-A, 2-C, 3-B, 4-D 1-D, 2-A, 3-C, 4-B 1-B, 2-D, 3-A, 4-C None 2. 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 3. 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. None of these. In the direction of motion of the body. In the direction perpendicular to the motion of the body. None 4. An object maintains its motion under the continuous application of ________force A strong A balanced An unbalanced A weak None 5. Principle of rocket is based on Newton's ......... law of motion. Third Second First None None 6. 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-C, 2-B, 3-D, 4-A 1-B, 2-D, 3-A, 4-C 1-A, 2-C, 3-B, 4-D 1-D, 2-A, 3-C, 4-B None 7. What is the action reaction pair when we walk on the floor? Air resistance, force applied by road on your feet Your feet exerts force on road, road reverts equal force back, None of these Air resistance, muscular force None 8. Which of the following uses the principle of conservation of momentum? All of these Ballon moves upwards when burst or when air is expelled out of it Motion of rockets and jet engines Gun recoils after firing None 9. If an object experiences a net zero unbalanced force, then the body can be accelerated will always remain at rest cannot remain at rest moves with a constant velocity None 10. 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? 10ms −1 5ms −1 None of these 20ms −1 None 11. What happens when some children try to push a box on a rough floor? The box moves with a little force None of these The box will move regardless of the force given The box does not move with a small force None 12. What is the product of force and the time for which force acts known as? Impulse of force Inertia Acceleration Momentum None 13. 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-D, 2-A, 3-C, 4-B 1-B, 2-D, 3-A, 4-C 1-C, 2-B, 3-D, 4-A None 14. Identify the incorrect statement. The weight of a body always acts towards the centre of the Earth. The tension of a string always pulls a body. Frictional force always acts parallel to the surface of contact. The spring force always pushes a body. None 15. Choose the correct statement from the following:Weightlessness of an astronaut moving in a satellite is a situation of Zero mass Zero g Free fall No gravity None 16. 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 Velocity is proportional to the force exerted on the ball. Ayush did not hit the ball hard enough 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 17. A bullet weighing 50 gram leaves the gun with a velocity of 30m/s.the ratio of their momentum is: 1:1 1:3 2:1 1:2 None 18. 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 A statement B neither statement A nor B both the statement a and b None 19. How much force acts on body whose momentum is constant (i.e. = constant)? 2p/t p/2t Zero None None 20. When a toothpaste tube is squeezed, it's shape changes. The force responsible for this is an example of _______. Centripetal force Unbalanced force Tangential force Balanced force 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.
