Sally applies a horizontal force of 500 N with a rope to dtag a wooden crate across a floor with a constant speed. The rope tied to the crate is pulled at an angle of 67.5 degrees. a) How much force is exerted by the rope on the crate? b) What work is done by Sally if the crate is moved 30.0 m? c) What work is done by the floor through force of friction between the floor and the crate?

Question

Sally applies a horizontal force of 500 N with a rope to dtag a wooden crate across a floor with a constant speed.  The rope tied to the crate is pulled at an angle of 67.5 degrees.  a) How much force is exerted by the rope on the crate? b) What work is done by Sally if the crate is moved 30.0 m? c) What work is done by the floor through force of friction between the floor and the crate?

Here is what I know: Work = Force x Distance and being as there is not a change in velocity there is not a net force.  Therefore, Force applied = Force of friction.  Once work is found the other two questions should be easy to answer.

drwls · Accepted Answer

The 500 N Sally applies must be the horizontal component of the appied force, not the total force (which is the ripe tension)

The horizontal force component is
T cos 67.5 = 500 N
Therefore T = 1306 N
b) Sally's Work = (horizontal force component) x (distance moved)
= 500 N x 30 m = ___ J
c) -(Work done by Sally)

Einstein · Answer

Thank you!!