CBSE - Class 9th - Science - Ch 9 - Force and Laws of Motion - Question Bank

In the previous post, we learnt about Motion as an introduction of Physics in Class 9th Science units. In this chapter we shall delve deeper into Physics by Learning more about the various laws of motion and its associated numerical calculations which shall help us build our foundation of Physics and associated mathematics for Class 11th later.

CBSE - Class 9th - Science

Chapter 9 - Force and Laws of Motion

• What is Force?

• How does an Object move? Why do they move?

• What are Balanced and Unbalanced Forces? Explain by giving examples.

• What is Friction and Friction Force?

• State Newton's First Law of Motion.

• What is Inertia? Why is First Law of Motion also referred to as Law of Inertia?

• Take a Glass, a Card and a five rupees coin. Place the Coin over the Card and the card on top of Glass. When the card is horizontally flicked fast with the finger, the coin placed over it falls in the tumbler instead of going with the card. Why?

• What is mass? How is it related to Inertia?

• Define Momentum. What is its SI Unit?

• State Newton's Second Law of Motion.

• Give the Mathematical formulation of Newton's Second Law of Motion.

• While trying to catch cricket ball, why does the fielder in the ground gradually pulls his hands backward along with the moving ball?

• A Force is applied from the back of a car of 500 kg at rest for 50 seconds to reach a velocity of 10 m/s. Calculate the force applied. If the same amount of force was applied for 25 seconds, what would have been the velocity of the car.

• Calculate the force needed to be applied to move:
• A Box of 10 kg at 3 m/s²
• A Box of 7 kg at 4 m/s²

• A Mini Truck weighing 1000 kg travelling at 72 km/h, applies brakes to stop. It took 5 second for it to come to rest. Calculate the amount of force exerted by the truck brakes.

• A force of 10 N can give a red color box an acceleration of 4 m/s². The same amount of force applied to a green box can give an acceleration of 5 m/s². Calculate the amount of acceleration that can be produced if both the object are tied together.

• State Newton's third law of motion.

• When a Gun is fired, why does the Shooter experiences some force pushing him backwards?

• What is the Law of conservation of momentum? Derive mathematical equation for the same.

• A Bullet weighing 20 g is fired from a Gun weighing 1 kg at a velocity of 100 m/s. Calculate the recoil velocity of the Gun.

• A Girl weighing 35 kg jumps with a horizontal velocity of 4 m/s over a stationary skating board weighing 5 kg. Assuming there is no other unbalanced force acting, what is their combined velocity as the skating board starts moving?

• Two cars approaching towards each other on road, collide at each other at high speed. After the collision, they got jammed to each other and both started moving in one direction for some time. The first car coming from Left side weighed 500 kg and had a velocity of 4 m/s. The second car coming from Right side weighed 800 kg and had a velocity of 2 m/s. Assuming the friction to be negligible, In which direction does both the cars move after their collision and at what velocity.

I hope these questions would help stay better prepared for exams. For solutions to the above questions, do comment below your thoughts and let me know.