set 2 MCQ Questions & Answers Detailed Explanation

Question : 1

The working principle of a washing machine is

a) Reverse osmosis

b) Dialysis

c) Centrifugation

d) Diffusion

Question : 2

Rahul takes 1 minute to raise a box to a height of 1 metre and Rohan takes 1/2 minute to do so. Comment on the energy by the two.

a) Energy spent by the Rohan is more

b) Energy spent by both Rahul and Rohan is same.

c) Energy spent by the Rahul is more.

d) Cannot be said

Question : 3

A man getting down a running bus, falls forward because

a) he leans forward as a matter of habit

b) due to inertia of motion upper part of body continues to be in motion in forward direction while feet come to rest as soon as they touch the road

c) due to inertia of rest, road is left behind and man reaches forward

d) of the combined effect of all the three factors stated in (a), (b) and (c)

Question : 4

A gymnast takes turns with her arms & legs stretched. When she pulls her arms and legs

a) the angular velocity stays constant

b) the moment of inertia decreases

c) the angular velocity decreases

d) the angular momentum increases

Question : 5

Assertion (A):
A man standing on a completely frictionless surface can propel himself by whistling.
Reason (R) :
If no external force acts on a system, its momentum cannot change.

a) A is true but R is false

b) Both A and R are true but R is not a correct explanation of A

c) Both A and R are true and R is the correct explanation of A

d) A is false but R is true

Question : 6

The force exerted by the floor of an elevator on the foot of a person standing there, is more than his weight, if the elevator is

a) going up and slowing down

b) going up and speeding up

c) going down and slowing down

d) either (a) or (b)