A man pulls a block of ice 10 m across a frozen lake by means of a rope attached at one corner. The man applies a force of 46.5 N at an angle 25above the horizontal. The force of friction between the block and the ground is 12.6 N. How much net(total) work was done on the block?

295.4 J.

Explanation:

From the question,

The net work done on the block = work done against friction minus the work done on the block to move it across the frozen lake.

W = (FcosФ-F')d Equation 1

Where W = total work done on the block, F' = force of friction, d = distance, F = force applied to the block, Ф = angle between the force and the horizontal, d = distance.

Given: F' = 12.6 N, F = 46.5 N, d = 10 m, Ф = 25°

Substitute into equation equation 1

W = (46.5cos25°-12.6)10

W = (42.14-12.6)10

W = 295.4 J.

kepler used the data from tycho blahe (his mentor) to construct the laws of planetary motion.