Question

Suppose that a 30.0 kg object is moving at 12 m/s when a force of 400 Nisapplied in the opposite direction of the motion of the object make theobject to slow down to a speed of 4 m/s. How long was the force appliedfor on the object?

Answer 1

Given:

The mass of the object is m = 30 kg

The initial velocity is

$v_i=\text{ 12 m/s}$

The final velocity is

$v_f=\text{ 4m/s}$

The force applied is F= -400 N as the force is applied opposite to the direction of motion.

To find the time for which the force was applied.

Explanation:

The time can be calculated as

$\begin{gathered} F\times t=mv_f-mv_i \\ t=\frac{m(v_f-v_i)}{F} \\ =\frac{30(4-12)}{400} \\ =0.6\text{ s} \end{gathered}$

Final Answer: The force was applied on the object for 0.6 s