Important questions for Class 9 science force and laws of motion
- The people in the bus are pushed backwards when the bus starts suddenly due to:- (a) Inertia due to Rest (b) Inertia due to Motion (c) Inertia due to direction (d) Inertia.
- If the force acting on the body is zero. Its momentum is :- (a) zero (b) constant (c) Both (d) None
- The inability of the body to change its state of rest or motion is :- (a) Momentum (b) Force (c) Inertia (d) Acceleration.
- Which law explains swimming? (a) Newton’s first law (b) Newton’s second law (c) Newton’s third law (d) All of these
- Why does the passenger sitting in a moving bus are pushed in the forward direction when the bus stops suddenly?
- Why does the boat moves backwards when the sailor jumps in the forward direction?
- Derive the law of conservation of momentum from Newton’s third law?
- An astronaut has 80 Kg mass on earth. What is his weight on earth? what will be his mass are weight on mars where g = 3.7 m/s2
- A boy throws a stone up with a velocity of 60 m/s. How long will it take to reach the maximum height (g = -10m/s2) What will be the maximum height reached by the stone? What will be its velocity when it reaches the ground?
- A certain particle has a weight of 30N at a place where the acceleration due to gravity is 9.8m/s2 What are its mass and weight at a place where acceleration due to gravity is3.5m/s2
- What will be its mass & weight at a place where acceleration due to gravity is zero? Why does a person while firing a bullet holds the gun tightly to his shoulders?
- A car is moving with a velocity of 16m/s when brakes are applied. The force applied by the brakes is 1000N. The mass of the car its passengers is 1200Kg.
- How long should the brakes be applied to make the car come to a halt?
- How for does the car travel before it comes to rest?
- A body of mass 2Kg is at rest at the origin of a frame of reference. A force of 5 N acts on it at t = 0. The force acts for 4S and then stops. What is the acceleration produced by the force on the body. What is the velocity at t= 4s
- Newton’s first law of motion is also called:-(a) Law of Inertia (b) Law of Momentum (c) Law of Action & Reaction (d) None of these
- If the friction acting on the body is more the body will move:-(a) More speedily (b) Less speedily (c) Same speed (d) None of these
- The S.I. unit of weight is :- (a) Newton (b) Newton m (c) Newton/sec (d) Newton m/s
- State Newton’s first law of Motion?
- A body of mass 5Kg starts and rolls down 32m of an inclined plane in 4s. Find the force acting on the body?