Question

give reason
(b) It is easier to push a lighter box than a similar heavy box on the same floor
(c) The force, needed to start a cart, is (somewhat) greater than the force
needed to keep it moving with a uniform speed.
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Answer 1

because of force acting on unit

Answer 2

(b) It is easier to push a lighter box than a similar heavy box on the same floor because the mass of the lighter box will be less thus the force required to push it will be less and thus,the frictional force acting on the box will be less and it will move easily.(Using Newton's Third law of motion