Question

Assertion: Pulling a lawn roller is easier than pushing it.
Reason: Pushing increases the apparent weight and hence the force of friction.

A. Both Assertion and Reason is true and Reason is the correct explanation of Assertion.
B. Both Assertion and Reason is true and Reason is not the correct explanation of Assertion.
C. Assertion is true, but Reason is false
D. Assertion is false, but Reason is true

Answer 1

Hint:Use the concept of force applied in horizontal and vertical direction while pushing and pulling of a lawn roller. Then find the change in weight of the body that is the lawn roller here with respect to the horizontal and vertical force applied on the body while pushing and pulling.

Formula used
Horizontal force, ${F_H} = F\cos \theta $
Vertical force, ${F_V} = F\sin \theta $


Complete answer:
Here, there are two cases of pulling and pushing a lawn roller.
Case1: Pulling
When we applied force F at an angle $\theta $ then we get two component of force;
Horizontal force, ${F_H} = F\cos \theta $
Vertical force, ${F_V} = F\sin \theta $
This vertical force will act in the opposite direction of weight.
Therefore, the apparent weight = $mg - F\sin \theta $
That means the weight will decrease. Hence, pulling becomes easier.
Case2: Pushing
When we applied force F at an angle $\theta $ in case of pushing then we get two component of force;
Horizontal force, ${F_H} = F\cos \theta $
Vertical force, ${F_V} = F\sin \theta $
But here this vertical force will be in the direction of weight.
Therefore, the apparent weight = $mg + F\sin \theta $
That means the weight will increase. Hence, pushing becomes difficult.
Thus, Assertion and Reason both are true.

Hence, the correct answer is Option A.


Note: Be careful of the vertical component of the force applied on the body that is a lawn roller here, it is the deciding factor as the direction of the vertical force will increase or decrease the weight of the body and then we get the apparent weight which make pulling easier and pushing difficult.