Download Energy lab Day 8 KEY

Energy lab - To verify the Law of Conservation of Energy.
Name ___________________________
Pre Lab questions to be answered
Hour ______________
1. What is the Law of Conservation of Energy?
The energy neither can be created nor destroyed
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2. What are the units of work, kinetic energy and potential energy?
joule
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3. What quantities does potential energy depend on?
mass, gravity, and height
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4. Does mass affect the velocity of the freely falling object? If your answer is yes, explain why. If not
then what are the factors that affect the velocity of a freely falling object?
No, mass does not affects velocity of a freely falling object. Velocity of a freely falling object
depends on gravity and the distance it is falling through.
Procedure
1. Find the mass of the ball and put it in the table given below. If your mass is in grams, convert it
into kilograms.
2. Mark a spot as “C” (0 meter) and “A” (2 meters) on the wall.
3. Drop the ball from mark “A” to mark “C” and time it. Do it for 10 trials.
4. Calculate the initial potential energy of the ball at mark “A”.
PE = m (10 m/s2)(2 m)
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5. Fill in the chart below:
Mass of the ball
in kilogram ‘kg’
Trial
1
2
3
4
5
6
Time for the ball
to go from ‘A’ to ‘C’
Calculate the Average Time of the
ball to go from ‘A’ to ‘C’.
Add all the times and divide by 10
1.5 s
3.5 s
.
. +
.
.
.
7
8
9
10
Average Time = _____________
Calculate the velocity of the ball at the bottom of the fall. (You want to find the velocity of the ball
at the bottom in order to calculate the kinetic energy of the ball at the bottom.) Remember when
you are holding your ball, the initial velocity is zero.
Use the average time of the ball you have calculated to find the
velocity of the ball at the bottom ‘C’.
vf = vi + g t
vf = 0 + (9.8 m/s2)(average time)
Fill in the chart below and find the potential energy and kinetic energy at each point:
Potential
Kinetic Energy at ”A”
Velocity @ “A”
Total Energy at “A” = K.E + P.E
Energy at “A”
at the top
Same as #4
zero
Potential
Energy at “C “
zero
Kinetic Energy at “C”
Same as #4
zero
Velocity @ “C” at the
bottom
This should be the
same as the final
velocity they found
earlier.
Same as #4
Total Energy at “C” = K.E +P.E
Same as #4
Compare the Results; Total Energy at “A” Total Energy at “C”
The total energy should be exactly the same. It will not change!
Conclusion: Using complete sentences explain the relationships involved with PE & KE. Use your
data to support your conclusions.
Their PE & KE will exchange places and their data should support this.
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