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This quix is to be delivered to and done by students in the class room under instuctor's supervision. A block of mass M = 8kg is held at a height h = 0.2 m above a vertical spring of length L = 0.6 m in an arrangement as shown. Given the sprign constant K = 864 N/m, the block is droppd on top of the spring. The mass M compresses the spring by an amount d before it stops going down further then bounces bacj upward.. Write the expression for the Elatic P.E. stored in the spring at the lowest position. Write the expression for the loss in gravitational P.E. by the time M reaches the lowest position. Hence claculate the deformation d.
Explanation / Answer
a)
Elastic PE=(1/2*k*d^2) where dis the compression,
b)
Let the reference point be the ground,
KE(i)+PE(i)=KE(f)+PE(f)
0+Mg(0.8)=1/2k(d^2)+Mg(0.6-d)
Mg(0.2)=432*d^2-Mgd
let g=10m/s^2
16=432*d^2-80d
The equation is
432d^2-80d-16=0
Solving this quadratic equation gives d
27d^2-5d-1=0
Solve the equation