New Trust Science Academy         

Physics  9^th

 Phase-1                                                                                                                             unit : 3

Name: ______________                                                                                                      Date:____________________

Tick the correct answer.

1. In which case it is easy for the tyre to roll over?

• Rough ground               smooth ground            c. both a & b          d. none

1. Friction coefficient friction of steel and steel is

• 8                                       b. 0.18                   c. 0.008                 d. none

1. Which of the following material lowers friction when pushed between metal plates?

• Water                               oil                      c. air                           d. none

1. To walk or run friction is needed to push the ground

• Forward                         backward               c. both a & b                  d. none

1. How much force is required for making acceleration 2.5ms^-2 when a mass of object is 8 kg?

• 10N                                 20N                   c. 30N                    d.40N

Give short answers.

1. What is the law of conservation of momentum?
2. Describe ways to reduce friction.
3. Why does a passenger move outward when a bus takes a turn?
4. What is law of inertia?
5. Force acting on a body of mass 5kg produces a acceleration of 10ms^-2. What acceleration the same force produce in a body of mass 8kg?

Long questions.

1. A bullet of mass 20g is fired from a gun with a muzzle velocity 100ms^-1. Find the recoil of the gun if its mass is 5kg.
2. How much is the force of friction between a wooden block of mass 5kg and the horizontal marble floor? The coefficient of friction between wood and the marble is 0.6.

Best of luck…!