The lab below consists
of three different stations.
I put out several setups of the two stations with the bouncy
and non-bouncy balls. The students complete this part of the
experiment with a partner. I
stay with the tennis ball cannon station and monitor it closely.
I get groups of about 6 students at a time to work with the cannon. The bouncy and non-bouncy balls are sold in several different
catalogs as “happy & unhappy balls” for around
$4 a pair. - Andy
Ball Cannon as described in The Dick and Rae Physics Demo
Notebook on page M-562.
graphing calculator, CBL, and Vernier Photo gate
an index card to the top of the cannon so it resembles a fin.
up the equipment as shown in the diagram.
- The photo gate is arranged so the index card passes through the photo
the card breaks the beam just as the ball exits the cannon. In
reality, if the
friction is low the photo gate can be set back a bit.
up the photo gate system to record the time it takes the
card to pass through the beam.
- Put the tennis ball in the cannon
the flammable material in the cannon
sure down range is clear
I R E ! !
By measuring the length of the index card you can calculate the speed
of the cannon.Show
you need the mass of the cannon and the ball. You can then solve for the velocity of the ball using conservation
of momentum. (Note: if Vcannon is + then Vball
is - )
Show your work!
Measuring Coefficient of Elasticity
- One bouncy
& one non bouncy ball &
one ball of another material
- Meter stick
- Hold the meter stick with
the 0 cm mark on the floor.
- Hold a ball with the bottom of the ball even with the 100 cm mark.
- Drop the ball and measure
the height that it bounces back up off of the floor.
- Repeat this 10 times and
determine the average.
- Calculate the coefficient
- Repeat for the two other
3. What would a 100% elastic ball do?
What would a 0% elastic ball do?
4. Under what conditions can you have 100% elastic collisions?
5. Is it possible to have 100% inelastic collisions? Give an example
6. How does a physicist’s definition of elastic differ from
the everyday use of the term?
and Inelastic collisions
• one bouncy & one non bouncy ball
• small wooden rectangular block
• section of hot wheels track
up the equipment as shown.
the bouncy ball to roll
down the hill and strike the ball.
Measure how far the block is shoved.Record your observations
of what the ball and block do as they collide.
the experiment with the non bouncy ball. Release it from the same height on the ramp. Measure how far
the block is shoved. Record
your observations of what the ball and block do as they collide.
- Since these balls are released from the same height they will impact
the block with the same speed. The
balls also have very nearly the same mass.
7. Which ball strikes the block with the
greater force? How do you
8. Which ball has the greatest impulse during collision? How do
Identify each of the collisions as elastic or inelastic.
Draw a before and after picture for each collision. Write the equation
showing conservation of momentum for each collision.
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