- #1

Emperor

- 11

- 0

## Homework Statement

Objects A (2.0 kg), B (1.0 kg), and C (1.0 kg) are pushed up a ramp, which is 4.0 m and 1.2 m high. The applied forces are parallel to the ramp with magnitudes of 9.8 N on A, 4.9 N on B, and 3.1 N on C.

## Homework Equations

Eff = W(output) ÷ E(Input) x 100%

W = F x d

E(potential) = mgh

## The Attempt at a Solution

Efficiency of A:

W(output) = 9.8 N x (4 + 1.2) = 50.96 J

E(potential) = 2 x 9.8 x (4 + 1.2) = 101.92 J

Eff = 50.96 ÷ 101.92 x 100 = 20% Efficiency

I know I'm probably over-thinking this one tiny equation but the thing is, I've spent 1 and a half hours on this question alone. The answers I'm supposed to get are "A: 60%, B: 60%, C: 95%" but I can't get anywhere close to them no matter what I do. Maybe its because I forgot how to add the ramp components together, but I thought that was correct. I resorted to guessing as well, but literally no combination of numbers can get me to that answer; its inconceivable for me. I also have a formula sheet on me as well, but I don't know which one to use. This is also literally the only question on my review sheet that I cannot understand at all... Like I said, I think I'm definitely over-thinking it. May someone enlighten me on my mistakes?