Astudent gives a 5.0 kg box a brief push causing the box to move with an initial speed of 8.0 m/s along a rough surface. the box experiences a friction force of 30 n as it slows to a stop. how long does it take the box to stop?

The time taken to stop the box equals 1.33 seconds.

Explanation:

Since frictional force always acts opposite to the motion of the box we can find the acceleration that the force produces using newton's second law of motion as shown below:

Given mass of box = 5.0 kg

Frictional force = 30 N

thus

Now to find the time that the box requires to stop can be calculated by first equation of kinematics

The box will stop when it's final velocity becomes zero

Here acceleration is taken as negative since it opposes the motion of the box since frictional force always opposes motion.