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1. In this week’s lab you examined the
conservation of energy by observing a mass start with all gravitational
potential energy, have it convert much of it to kinetic energy as it moved
and then have it convert some of that energy back into gravitational
potential energy. For this
conservation of mechanical energy to be accurate you
had to make a major assumption about the process occurring in lab, what was
this assumption? |
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For conservation
of mechanical energy to occur, there must be no
non-conservative forces acting.
So we have to ignore air resistance and any
frictional forces acting in the apparatus. |
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2. Based on your results, was this a
reasonable assumption? |
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It should have
been a fairly reasonable assumption given that the
masses were not moving at very large speeds.
There are few ways to get friction with the string pendulum. |
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3. A mass of 0.025 kg falls a distance of
0.35 m, what is the change in the gravitational potential energy of the
mass. Please use units of joules and
include a sign. |
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4. A
mass of 0.025 kg has a kinetic energy of 0.090 J, what is the mass’s speed
(in units of m/s, please)? |
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OVER ŕ |
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3. A mass of 0.045 kg is attached to a
string (L = 0.65 m) and allowed to swing as a pendulum. When the mass is at the bottom of the
swing, draw a free body diagram. |
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4. Assume the mass (m = 0.045 kg) has a
speed of 4.35 m/s at the bottom of the swing (L = 0.65 m), how high above the bottom of
the swing would the mass travel before pausing momentarily
and then swing back the other way? |
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5. Again assume the mass (m = 0.045 kg) has
a speed of 4.35 m/s at the bottom of the swing, (L = 0.65 m) what is the
tension in the string? |
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