Posted by **Alex** on Sunday, October 21, 2012 at 5:01pm.

A 2.42kg block starts from rest at the top of a 22.9◦ incline and accelerates uniformly down the incline,moving 2.41m in 2.14s. The acceleration of gravity is 9.81m/s2. a) What is the magnitude of the acceleration of the block?

Answer in units of m/s2

b) What is the coeﬃcient of kinetic friction

between the blockand the incline?

c) What is the magnitude of the frictional

force acting onthe block?

Answer in units of N

d)What is the speed of the block after it slides

the distance of 2.41?

Answer in units of m/s

- Physics -
**bobpursley**, Sunday, October 21, 2012 at 5:35pm
a. you know the final speed (twice average). Vf=2*2.41m/2.14s

Vf^2=Vi^2+2ad solve for acceleration a.

b. do energy concepts

KEfinal=KE initial + PEinitial-PEfinal-Frictionenergy

or

1/2 m vf^2=0 + mg 2.41/sinTheta -0-friction energy

solve for friction energy

then, Frictionenergy=mu(mg*cosTheta)

solve for mu.

c. friction energy=force*distance solve for force.

d. See a.

- Physics -
**Alex**, Sunday, October 21, 2012 at 5:56pm
Can you tell me the answer for c and d. I got the one for a and b correct but c says it's not correct. I put 21.96N.

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