Warm-up
• The extent of my disappointment in you is
beyond words…. Do Not TALK!!
• You are to write a letter of apology to Mrs.
Gleason for having to clean up the MESS you
guys left in the library on Friday.
• Unfortunately, to those who were on point on
Friday the rest of the class ruined it for you….
Warm up
• If I told you that within a closed system a
system only has 3 forms of energy KE, GPE,
and HE and this system had the following:
– 1542 J of total energy
– 134 J of Kinetic Energy
– 1045 J of GPE
How much HE would the system have? What law
would help explain this?
Elastic Potential Energy
• When an elastic material is stretched or
compressed, a force is applied to transfer energy
to that material.
• The elastic force and the distance that the elastic
is stretched or compressed are related to the
properties of the material and are known as the
elastic constant.
• The elastic constant is different for every elastic
material.
• All elastic material have an elastic limit, which is
the point the material will no longer return to it’s
original shape and no longer behave like an
elastic material
Newton’s Second Law
• Net Force = Mass x Acceleration (F = MA)
• As force increases, acceleration increases
• As mass increases, acceleration decreases
Let’s Investigate
• You will need the following:
– One track
– 2 blocks
– 1 cars
– weights
– Meter stick
Trial 1
Setting
Mass
Distance Force
1
.1 kg
1N
2
.1 kg
3N
3
.1kg
6N
Work
Acceleration
Trial 1
Observe the motions of the carts with no Weight
after you release the plunger by tapping on it
with a pencil on setting 1.
Measure the distance your car goes up the ramp
Repeat for setting 2 and 3
Assume that the force from the plunger is :
1 Newton at setting 1
3 newtons at setting 2
6 newtons at setting 3.
Each cart has a mass of 0.1 kg.
• What is the work done by cart 1 at each setting
• What is the acceleration on cart 1?
Trial 2
Add the 20g mass to the cart. Record the
distance the cart traveled up the ramp at all
settings
the mass you added to the red cart is 0.020 kg,
so the new mass of cart is __________.
• What is the work done by cart 1 at each
setting
• What is the acceleration on the cart?
• How did the acceleration change when the
mass increased?
Trial 3
• Add the 200 g mass. Record the distance the
cart traveled up the ramp at all settings
• What is the work done by cart 1 at each setting
• What is the acceleration on cart?
• How did the acceleration change when the force
increased?
Lab Report
• Introduction- restate our purpose and
hypothesis and add some more details of
what we are testing- using EPE we are testing
newton’s second law.
• Procedure- Repeat what we did
• Data- Put all data in table like this:
Setting
Mass
Distance Force
1
.1 kg
.3 m
1N
2
.1 kg
.63 m
3N
3
,1kg
1.11 m
6N
Work
Acceleration
Lab Report
• Analysis- graph the distance for each trial!
• Conclusion: How does Mass affect acceleration?
Did you prove or disprove your hypothesis? What
is EPE? How did we use it? Draw conclusion
based on your data!