I need help on this problem and it has been driving me crazy. It has 3 parts, so

Question

I need help on this problem and it has been driving me crazy. It has 3 parts, so the reward will be very high to the person who correctly answers the question. Here it is:

A block is released from point A on a track ABCD as shown in the figure. Point A is higher than points B, C, and D. The track is

frictionless except for a portion BC which has a coefficient of friction %u03BC. The block travels down the track and hits the spring with spring constant k. The acceleration of gravity is 9.8 m/s2 . Please see attached figure.

A) If the spring compresses 6 cm, find the coefficient of friction %u03BC.

B)For this value of %u03BC, to what height h%u2032 will the block rise when it returns to point E ? Answer in units of m.

C)Suppose %u03BC is changed. After releasing the mass m from point A, the mass travels over the rough portion of the track BC, bounces off the spring, and travels a distance 2.7 m part way back across the rough portion of the track to stop at point F .

Under these conditions, what is the value of %u03BC?

Explanation / Answer

A block is released from point A on a track ABCD as shown in the figure. Point A is higher than points B, C, and D. The track is

1)Energy stored in spring = 0.5*k*A^2 = 0.5*239*0.06^2 *10^3= 430.2

Energy at height h=4.2 m = m*g*h = 12*9.8*4.2

So energy loss = difference = 493.92 - 430.2 = 63.72

Now work done by friction == mew*m*g*3.2

mew*12*9.8*3.2 = 63.72

mew = 0.169

B)

Energy lost again will be 63.72 J

so m*g*h = 430.2 -63.72

h = 3.116 m

C).so energy lost = work done by friction

m*g* h = mew*m*g*s

s= 3.2+2.7 = 5.9

mew = h/s = 4.2/5.9 = 0.712

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