Answer to Question #289489 in Physics for hazel

Question

4. A constant force of 45N acts on a 15 kg box. The direction of the force is to the left. If the box is originally at rest, what will be its velocity after 5s? Indicate the magnitude and direction of the velocity.

Answer 1

Given:

$F=45\:\rm N$

$m=15\:\rm kg$

$t=5\:\rm s$

$v_0=0\:\rm m/s$

The acceleration of a box

$$a=\frac{F}{m}=\frac{45}{15}=3\:\rm m/s^2$$

The velocity of a box after $5\:\rm s$

$$v=v_0+at=0+3*5=12\:\rm m/s\quad (toward\; left)$$