posted by Rob .
A student applies a force of magnitude 39.0 N at an angle of 22.6o with the horizontal to push a
4.00-kg textbook 1.00 m across a table from rest to a final speed of 1.75 m/s. Find the work
done by friction on the textbook.
work doneonbook= 1/2* 4 *1.75^2
work friction= work applied-work done
39 cos22.6*(1 meter) is the work done by the force, in joules. Subtract the final kinetic energy from that. That will be the work done against friction.
The work done. BY friction is negative