set 4 MCQ Questions & Answers Detailed Explanation

Question : 1

A rubber ball dropped from 24 m height loses its kinetic energy by 25%. What is the height to which it rebounds.

a) 18 m

b) 12 m

c) 6 m

d) 24 m

Question : 2

Two persons do the same amount of work, one in 10 s and the other in 20 s. Find the ratio of the power used by the first person to that by the second person.

a) 5 : 2

b) 2 : 1

c) 6 : 4

d) 4 : 3

Question : 3

A cannon after firing recoils due to

a) Newton’s third law of motion

b) backward thrust of gases produced

c) conservation of energy

d) Newton’s first law of motion

Question : 4

When an incandescent electric bulb glows

a) the light energy is converted into electric energy

b) the electric energy is partly converted into light energy and partly into heat energy

c) the electric energy is completely converted into light

d) the electric energy is converted into magnetic energy

Question : 5

Which of the following is a vector quantity?

a) Displacement

b) Speed

c) Time

d) Distance

Question : 6

No work is done when

a) there is no component of force parallel to the direction of motion

b) a box is pushed along a horizontal floor

c) a nail is plugged into a wooden board

d) there is no component of force normal to the direction of force