set 4 MCQ Questions & Answers Detailed Explanation

Question : 1

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 : 2

A body weighs less at the equator than at the poles because:

1. earth rotates about its axis.
2. the ice cap at the poles increases gravitational pull.
3. equatorial diameter is greater than the polar diameter.
4. of some unknown facts.

a) 1 and 3

b) 1 and 2

c) 3 only

d) 4 only

Question : 3

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 : 4

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

Question : 5

A parachutist jumps from a height of 5000 metre. The relationship between his falling speed, v and the distance fallen through d is best represented as :

a)

b)

c)

d)

Question : 6

A composite disc is to be made using equal masses of aluminium and iron so that it has as high a moment of inertia as possible. This is possible when

a) the whole of the iron is kept in the core and the aluminium at the outer rim of the disc

b) the whole of aluminium is kept in the core and the iron at the outer rim of the disc

c) the surfaces of the disc are made of iron with aluminium inside

d) the whole disc is made with thin alternate sheets of iron and aluminium