What is the change in gravitational potential energy, in Joules?

Question

A 20.0 kg box slides up a 12.0 m long incline at an angle of 30.0 degrees with the horizontal. A force of 150 N is applied to the box to pull it up the incline. The applied force makes an angle of 10.0 degrees to the incline. What is the change in gravitational potential energy, in Joules?

Answer given;

a.2570

b.2350

c.1450

d.1180

which one is correct???

 

Answer 1

I assume the box started from an elevation of 0m.

 

ΔU_G = mgΔh = (20.0 kg)(9.8 m/s²)[(12 sin30º - 0)m] = 1176 J

 

The closest answer is (d).