Posted by magic 8 ball on .
A 20N crate starting at rest slides down a rough 5.0m ramp, inclined at 25 degress with the horizontal. 20j of energy is lost due to friction. what will be the speed of the crate at the bottom of the incline?
i need some help these one i don't know where to start
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PHYSICS  drwls, Tuesday, October 23, 2007 at 7:41pm
Is your @0N (the weight, M g) supposed to be 20N? I will assume so. If not, you provide the correct value.
The loss in potential energy is
M g * 5 sin 25 meters = 42.3 J
PE loss = friction + kinetic energy gain
42.3 = 20 + KE increase = (1/2) M V^2
(1/2) M V^2 = 22.3 J
M = 20 N/9.8 = 2.04 kg
V^2 = 2*22.3/2.04 m^2/s62
solve for V
ok the first time i did it i got 3.2m/s and the second time i did to double check it i got 4.7m/s which is right?

PHYSICS 
RJ,
4.7 m/s is the correct answer.