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