- #1
songoku
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Homework Statement
As shown in Figure 1, two objects A and B of the same mass m are moving on a horizontal plane without friction along x axis. The two objects are connected by a string of length l. The mass of the string is negligible, and the length is constant. At time t = 0, A is to the right of B at a distance of l / 2, (the string remains flabby), and A and B are moving in the same direction at velocities vA and vB, respectively (vA > vB). When the distance between A and B becomes l, the string is stretched tightly to its full length. Immediately afterwards, A and B approach each other, and then collide. Suppose that no energy is lost when the string is stretched to its full length, and the collision between A and B is elastic. Answer the following questions:
(a) Estimate the elapsed time T1 from t = 0 to the moment when the string is stretched to its full length.
(b) Find the velocities of A and B immediately after the string is stretched to its full length for the first time
(c) Estimate the elapsed time T2 from t = 0 to the first collision between A and B
(d) Find the velocities of A and B immediately after the first collision
(e) Calculate the time elapsed T3 from t = 0 to the moment when the string is stretched to its full length for the second time
(f) Draw the graph of vB(t) from t = 0 and t = T3
Homework Equations
kinematics
momentum
The Attempt at a Solution
(a) T1 = L / (2(vA - vB))
(b) I am not sure about this one. Will the speed be the same but opposite direction for A? So the velocity of A is - vA and velocity of B still vB?
Thanks