a box mass 5.0 kg is accelerated from rest by a force across a floor at 2.0m/s2 for 7s. find net work on box?

Answer 1

Work is
W = Force * distance * cos theta
where theta is the angle (if any) between the motion and the force. Like if you go 100 m dragging a dog on a leash that's reluctant to go with you. You're exerting a force on the line of the leash - say 30 degrees elevated from the floor - so the work is your force * 100 m * cos 30.

In this case, I'll assume theta is 0. I also have to assume that there is no friction. Need to calculate the force.
F = m*a = 5 kg * 2 m/s^2.
Also need the distance s.
S = (1/2)*a*t^2 = (1/2) * 2 m/s^2 * (7 s)^2

So W = 5 kg * 2 m/s^2 * (1/2) * 2 m/s^2 * (7 s)^2