The block in Fig. 7-11 a lies on a horizontal frictionless surface, and the spri

Question

The block in Fig. 7-11a

lies on a horizontal frictionless surface, and the spring constant is 54.0 N/m. Initially, the spring is at its relaxed length and the block is stationary at position x = 0. Then an applied force with a constant magnitude of 6.0 N pulls the block in the positive direction of the x axis, stretching the spring until the block stops. When that stopping point is reached, what are (a) the position of the block, (b) the work that has been done on the block by the applied force, and (c) the work that has been done on the block by the spring force? During the block's displacement, what are (d) the block's position when its kinetic energy is maximum and (e)the value of that maximum kinetic energy?

Explanation / Answer

HELLO!! A) Is a simple force problem Fnet = T - kx = ma = 0 (where T is the pulling force) x = T/k B) We know that work = the dot product of Force and Displacement so W = T*T/k*cos(0) C) We know that W = ?K. Because ?K was 0 we know that the total work must add to 0. So in this case the work done by the spring is the negative of the work done by the pulling force. D) We know that the block is in simple harmonic motion, so we know that this point is at x = 0. E) We know that Work non-conservative = the change in energy. There are no nonconservative forces at work in the system of the block and spring once the block is no longer being pulled so the total mechanical energy at any two points in the system must be the same. We will choose two points that have 0s so we can solve. Initial is fully stretched and final is equilibrium. Wnc = delta E Ei = Ef Ki + k*xi = Kf + k*xf Ki = 0 and K*xf = 0 so kxi = Kf = k*T/k = T

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.