- Sep 10, 2005
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Here's the question, much simpler from last time:
A mass of 0.081 kg hangs from a vertical spring in the lab room. You pull down on the mass and throw it vertically downward. The speed of the mass just after leaving your hand is 4.20 m/s.
(a) While the mass moves downward a distance of 0.09 m, how much work was done on the mass by the Earth? Include the appropriate sign.
(b) The speed of the mass has decreased to 3.28 m/s. How much work was done on the mass by the spring? Include the appropriate sign.
I've tried solving it by using change in Kinetic Energy = Work but I can't seem to get the right answer. Essentially I've been doing (1/2)*.081*(3.28^2-4.20^2)=W_earth + W_spring. I found W_earth to be 0.0714J did KE-W_earth to get W_spring, but that seems to be wrong.
Can someone who's familiar with doing these types of problems tell me what I'm missing?
A mass of 0.081 kg hangs from a vertical spring in the lab room. You pull down on the mass and throw it vertically downward. The speed of the mass just after leaving your hand is 4.20 m/s.
(a) While the mass moves downward a distance of 0.09 m, how much work was done on the mass by the Earth? Include the appropriate sign.
(b) The speed of the mass has decreased to 3.28 m/s. How much work was done on the mass by the spring? Include the appropriate sign.
I've tried solving it by using change in Kinetic Energy = Work but I can't seem to get the right answer. Essentially I've been doing (1/2)*.081*(3.28^2-4.20^2)=W_earth + W_spring. I found W_earth to be 0.0714J did KE-W_earth to get W_spring, but that seems to be wrong.
Can someone who's familiar with doing these types of problems tell me what I'm missing?
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