physics
posted by arriell on .
a girl pulls a 12.0 kg wagon along by exerting a force of 15.0 N on the wagons handle, which makes an angle of 20.0 degrees with the horizontal. Friction provides a force of 11.0 N in the opposite direction. How long does it take for the wagon, which is initially at rest, to reach a speed of 4.50 m/s?

Calculate the acceleration rate, a = F/m. F is the net force in the horizontal direction.
The time required is (4.50 m/s)/a
F = 15 cos 20  11 Newtons.