A man sits with his back against the back of a chair, and he pushes a block of m

Question

A man sits with his back against the back of a chair, and he pushes a block of mass m = 3 kg straight forward on a table in front of him, with a constant force F = 31 N, moving the block a distance d = 0.6 m. The block starts from rest and slides on a low-friction surface. (Due to the nature of this problem, do not use rounded intermediate values in your calculations—including answers submitted in WebAssign.)

CORRECT(a) How much work does the man do on the block? 18.6 Correct: Your answer is correct. J

CORRECT(b) What is the final kinetic energy K of the block? 18.5856 Correct: Your answer is correct. J

CORRECT(c) What is the final speed v of the block? 3.52 Correct: Your answer is correct. m/s

CORRECT(d) How much time t does this process take? .3406 Correct: Your answer is correct. s

NEED HELP(e) Consider the system of the man plus the block: how much work does the chair do on the man? 18.6 Incorrect: Your answer is incorrect. J

CORRECT (f) What is the internal energy change of the man? -18.6 Correct: Your answer is correct.

Now suppose that the man is sitting on a train that is moving in a straight line with speed V = 19 m/s, and you are standing on the ground as the train goes by, moving to your right. From your perspective (that is, in your reference frame), answer the following questions.

NEED HELP(g) What is the initial speed vi of the block?

NEED HELP(h) What is the final speed vf of the block?

NEED HELP(i) What is the initial kinetic energy Ki of the block?

NEED HELP(j) What is the final kinetic energy Kf of the block?

NEED HELP(k) What is the change in kinetic energy K = Kf Ki?

NEED HELP(l) How far does the block move (x)?

NEED HELP(m) How much work does the man do on the block?

NEED HELP(n) How far does the chair move?

NEED HELP(o) Consider the system of the man plus the block: how much work does the chair do on the man?

NEED HELP(p) What is the internal energy change of the man?

Explanation / Answer

Now suppose that the man is sitting on a train that is moving in a straight line with speed V = 19 m/s, and you are standing on the ground as the train goes by, moving to your right. From your perspective (that is, in your reference frame), answer the following questions. ?

(G)
Initial Speed of the Block, Vi = 19 m/s.
(H)
Final Speed of the Block, Vf = 19 + 3.52 =22.52 m/s

(I)
Initial Kinetic Energy of the Block, = 1/2*mVi^2
K.Ein = 1/2*3*19^2 J
K.Ein = 541.5 J

(J)
Initial Kinetic Energy of the Block, = 1/2*mVf^2
K.Ein = 1/2*3*22.52^2 J
K.Ein = 760.7 J

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