Question

A $3.0kg$ box slides on ice so smooth that the frictional force between the ice and box is zero. Air resistance is also zero. If the box is sliding at $4.0m/s$. How much force must be applied to the box to keep the box moving at $4.0m/s$?

• A. $3.0N$
• B. $29.4N$
• C. $0N$
• D. $4.0N$
• E. $39.2N$

Answer 1

Answer: (C)

$0N$

Since there is no force acting on the box in horizontal direction(neither frictional or air resistance), the acceleration of box is zero, and so it continues to move with same speed.

Hence no force needs to be applied to the box to keep it moving with same speed.

Correct answer is option C.