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The hand exerts a constant force of magnitude F Block B is now removed, so that

ID: 1367668 • Letter: T

Question

The hand exerts a constant force of magnitude F Block B is now removed, so that the right end of the spring is now directly in contact with the wall, as shown. During the interval from is to ts, block A is again pushed a distance da by a hand exerting a constant force FA. The wall exerts a force on the spring that varies with time but is always directed to B. the left. Let system AS consist of block A and the spring. Consider the interval from is to 14: 1. Is the net external work and the net external impulse done on system AS by external forces over this interval greater than, less than, or equal to that on system ABS over the interval from i to 12? Explain. Write an expression for the work done on block A by the hand over this interval in terms of the given quantities (ie, Fa, da, Is, and/or t4). Explain. 2. 3. What is the displacement of the left end of the spring during this interval? What is the displacement of the right end of the spring during this interval? Which of these displacements should be used to calculate the work done on the spring by the wall? Explain. Is the work done on the spring by the wall positive, negative, or zero?

Explanation / Answer

work done by the spring is always positive

because work done=1/2kx^2

work done=1/2k(x1^2-x2^2)

from t1 to t2 time

work done=force*displacement