A small mass m is tied to a ceiling of hight h=5l/4 by a string of length l and attached to the floor by a massless spring with spring constant k=16mg/l. When the mass is in its equilibrium position, the spring is stretched by an amount x=l/8. The mass is pulled to the side until the spring has a length s=3l/4 and released from rest. What is the speed of the mass as it passes through its initial position (as shown in the left hand figure).

MC answers are:
a) sqrt (6g/l)
b) sqrt (32gl)
c) sqrt (32gl/5)
d) sqrt (6gl)
e) none of the above

Our answer is v = sqrt (89gl/10)--even confirmation or a "nope, that's wrong!" would be appreciated.

Question

A small mass m is tied to a ceiling of hight h=5l/4 by a string of length l and attached to the floor by a massless spring with spring constant k=16mg/l. When the mass is in its equilibrium position, the spring is stretched by an amount x=l/8. The mass is pulled to the side until the spring has a length s=3l/4 and released from rest. What is the speed of the mass as it passes through its initial position (as shown in the left hand figure).

MC answers are:
a) sqrt (6g/l)
b) sqrt (32gl)
c) sqrt (32gl/5)
d) sqrt (6gl)
e) none of the above

Our answer is v = sqrt (89gl/10)--even confirmation or a "nope, that's wrong!" would be appreciated.

anonymous · Answer

|dw:1392097142452:dw|