A string with length L (m) and mass density ? (kg/m ) hangs over a massless pull
ID: 2137877 • Letter: A
Question
A string with length L (m) and mass density ? (kg/m) hangs over a massless pulley. Each end of the string has a point mass M attached. Initially, the ends of the string are distances x0 above and below their average position. The rope is given an initial speed v0 so that it will NOT eventually fall off the pulley. Calculate the value of this required initial speed, in terms of the given quantities. The acceleration of gravity is 9.8 m/s2. How will be required initial speed be affected if both point masses M approach 0 -- the only mass remaining in the string? How will the required initial speed be affected if the mass density of the string approaches 0 -- the only mass remaining at the ends of the string?
We have not gone over energy equations. This problem is supposed to involve differential equations.
Explanation / Answer
v^2 - u^2 = 2as
s= x0
u =0
v^2= 2*9.8*x0
hence initial velocity v= sqrt(2*9.8*x0)-----------------> ans
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