A 20.0 kg box slides down a 12.0 m long incline at an angle of 30.0 degrees with the horizontal.A force of 50.0 N is applied to the box in the upward direction.The applied force F makes an angle of 0.00 to the incline.If the incline has a coefficient of kinetic friction of 0.000,then the increase in the kinetic energy of the box is
A) 620 J.
B) 576 J.
C) 542 J.
D) 500 J.
E) 475 J.

Question

Quizplus · Accepted Answer

The increase in kinetic energy is calculated by considering the net work done on the box. The gravitational force component along the incline is m*g*sin(θ) = 20*9.8*sin(30) = 98 N. The net force along the incline is 98 N - 50 N = 48 N. The work done by this net force over 12 m is 48 N * 12 m = 576 J.

A 200 Kg Box Slides Down a 12