Atruck is hauling a 300-kg log out of a ditch using a winch attached to the back of the truck. knowing the winch applies a constant force of 2500 n and the coefficient of kinetic friction between the ground and the log is 0.45, determine the time for the log to reach a speed of 0.5 m/s.

0.128 s

Explanation:

We have to start by calculating the net force acting on the log. We have two forces:

- The constant pulling force, forward, of F = 2500 N

- The frictional force, backward

The frictional force is given by

where

is the coefficient of friction

m = 300 kg is the mass of the log

is the acceleration of gravity

Substituting,

So the net force acting on the log is

Now, we can find the acceleration of the log by using Newton's second law

where a is the acceleration. Re-arranging for a,

And finally we can find the time it takes for the log to reach a speed of

v = 0.5 m/s

by using the suvat equation:

where u = 0 is the initial speed and t the time. Solving for t,

u

explanation: