Posted by **em** on Wednesday, May 4, 2011 at 6:05pm.

Starting from rest, a 4.4 kg block slides 3.5 m down a rough 22.3o incline in 2.4 seconds. Determine the energy lost due to friction. (Hint: find the final kinetic energy and subtract that from the work done by gravity.)

Enter your answer here: J

- physics -
**drwls**, Wednesday, May 4, 2011 at 6:33pm
Your hint tells you how to do it.

The final velocity is twice the average velocity of 3.5/2.4 m/s, which would be

Vfinal = 2.92 m/s

Energy lost = M g H - (1/2) M Vfinal^2/2

You do not need to use the slope of the incline to get the answer. You COULD use it to get the kinetic friction coefficient.

- physics -
**bobpursley**, Wednesday, May 4, 2011 at 7:53pm
average velocity= distance/time=3.5/2.4 m/s

so final velocity= 2*averagevelociyt

and KEfinal= 1/2 m vf^2

height of ramp= 3.5sin22.3

mgh=you figure.

energy from friction= mgh- KEfinal

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