set 3 MCQ Questions & Answers Detailed Explanation

Question : 1

When a body is stationary

a) the combination of forces acting on it balances each other

b) the force acting on it not in contact with it

c) there is no force acting on it

d) the body is in vacuum

Question : 2

Which of the following is NOT an illustration of Newton's third law ?

a) Walking on floor

b) A cricket player lowering his hands while catching a cricket ball

c) Flight of a jet plane

d) Rebounding of a rubber ball

Question : 3

A ball is dropped from a satellite revolving round the earth at a height of 120 km. The ball will

a) fall down to earth gradually

b) continue to move with the same speed along the original orbit of satellite.

c) continue to move with same speed along a straight line tangentially to the satellite at that time.

d) go far away in space

Question : 4

What is the correct equation for finding the acceleration?

a) a = ${v + u}/t$

b) a = u + vt

c) a = ${v - u}/t$

d) a = ${v + u}/2$

Question : 5

When you compress a coil spring you do work on it. The elastic potential energy

a) disappears

b) decreases

c) increases

d) remains the same

Question : 6

A missile is launched with a velocity less than escape velocity. The sum of its kinetic and potential energies is

a) positive

b) negative

c) zero

d) may be positive, negative or zero