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sonutulsiani
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Homework Statement
A cube of mass m = 5 kg is released from rest and falls a height of h1 = 2 m before hitting a vertical spring which brings the cube to a stop (momentarily) after being compressed by h2 = 50 cm.
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Assume the spring has no mass, heating of the spring and the cube is negligible, and there is no air resistance.1. Which of the following statements are true for the system which includes Earth, the cube, and the spring: (There are more than 1 true answers)
A. The mechanical energy of the system is preserved.
B. The gravitational potential energy of the cube is converted into elastic potential energy of the spring at maximum compression.
C. The kinetic energy of the cube at the time of impact is equal to the elastic potential energy of the spring at maximum compression.
D. At no point during the motion of the cube will the net force on it be zero.2. Calculate the spring constant k = ____ N/m (use g = 9.81 m/s^2 and round your answer to the nearest integer).3. What is the speed of the cube at a height h3 = 20 cm below the point of impact?
A. 6 m/s.
B. 0 m/s.
C. 21 m/s.
D. 980 m/s.
Homework Equations
The Attempt at a Solution
For the first question, I think it is A and B?
I don't know about the 2nd and 3rd question. Please help