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ka A 4.80-kg block is set into motion up an inclined plane with an initial speed

ID: 2115383 • Letter: K

Question

ka

A 4.80-kg block is set into motion up an inclined plane with an initial speed of vi 8.40 m/s (see figure below The block comes to rest after traveling d 3.00 m along the plane, which is inclined at an angle of e 30.0% to the horizontal. (a) For this motion, determine the change in the block's kinetic energy. Enter a number. change in a quantity is defined as the final value minus the initial value. J (b) For this motion, determine the change in potential energy of the bloc system. k-Earth (c) Determine the friction force exerted on the block (assumed to be constant) (d) What is the coefficient of kinetic friction?

Explanation / Answer

a)

change in energy = 0.5*4.8*8.4^2 = -169.34 J


b)

change = 4.8*9.8*3*sin(30 degrees) = 70.56 J


c)

friction = (169.34-70.56)/3 = 32.9 N


d)

coefficient = 32.9/(4.8*9.8*cos(30 degree)) = 0.807