You don't need to worry about friction to know how much work was done by, or against, gravity. It equals the change in potential energy, which is
M g * (change in elevation).
Put a minus sign in front of it to get the work done BY gravity.
The change in elevation is
H = 8.1 sin 14.6 meters
A 10.2 kg crate is pulled up a rough incline
with an initial speed of 1.5 m/s. The pulling
force is 123.0 N parallel to the incline, which
makes an angle of 14.6◦ with the horizontal.
The coe�cient of kinetic friction is 0.39 and
the crate is pulled a distance of 8.1 m.
The acceleration of gravity is 9.81 m/s2 .
a) Find the work done by Earth’s gravity
on the crate. Answer in units of J.
1 answer