A 4.0-kg block starts from rest and slides 5.0 m down a plane inclined at 60º to the horizontal.The coefficient of kinetic friction between the surface and the block is 0.20.The work done by friction on the block is
A)98.0 J
B)19.6 J
C)3.92 J
D)3.40 J
E)64.0 J

Question

Quizplus · Accepted Answer

The work done by friction on the block can be found using the equation:

work done by friction = force of friction x distance

The force of friction can be found using:

force of friction = coefficient of friction x normal force

The normal force can be found using:

normal force = 4.0 kg x 9.8 m/s^2 x cos(60º) = 19.6 N

The force of friction can be found using:

force of friction = 0.20 x 19.6 N = 3.92 N

The distance traveled by the block is 5.0 m.

Therefore, the work done by friction on the block is:

work done by friction = 3.92 N x 5.0 m = 19.6 J

So the answer is B.

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