Download The Gravitron! 1.1 Observe and Reason 1) Roll a bowling ball along

Zubrzycki: Circular Motion 1
The Gravitron!
1.1 Observe and Reason
1) Roll a bowling ball along a smooth floor. As the ball moves, tap it with a rubber mallet,
trying to make it move in a circle. The top-view diagram shows your successful attempt.
2) Tie an object to a string and swing the object around at a constant speed in a horizontal
circle.
3) Place a marble along the inside edge of a container. Give one hard initial push on the marble
and observe its motion.
a) Draw a front view force diagram for the circling object for each situation.
b) Indicate the direction of the unbalance of forces for each situation.
c) Can you determine a pattern based on the three experiments? If so, what is it?
1.2 Testing
Go to the webpage below but DO NOT watch the video right away. First, answer the questions
on the webpage. This is a testing experiment, so make sure you make a prediction before you
watch the video.
http://paer.rutgers.edu/pt3/experiment.php?topicid=5&exptid=57
A
B
E
C
D
Zubrzycki: Circular Motion 1
1.3 Represent and Reason
Three small toy cars travel at constant speed in identical-radii horizontal circular paths. Car A
moves at speed v, car B at speed 2v, and car C at speed 3v. Use the graphical velocity subtraction
method to determine how the magnitude of the acceleration of the cars depends on their speeds.
Remember that acceleration is ∆ v /∆t and that you need to compare the velocity change ∆ v
vectors for the three speeds and also the time interval ∆t needed for the velocity changes in each
of the three cases.
2v
v
x
3v
x
x
x
1.4 Represent and Reason
Two small toy cars travel at the same constant speed in horizontal circular paths. Car I moves in
a circle of radius r and car II in a circle of radius 2r. (a) Use the graphical velocity change
method to determine how the magnitude of the acceleration of the cars depends on the radii of
the circles. Do not forget to consider the time intervals needed for the velocity changes.
v
x
v
x
x
x
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Zubrzycki: Circular Motion 1
1.5 Represent and Reason
An athlete whirls a 7 kg hammer 1.8 m from the axis of rotation in a horizontal circle. If the
hammer makes one revolution is 1.0 s, what is the centripetal acceleration of the hammer? What
is the force exerted by the chain on the hammer?
1.6 Represent and Reason
What is the direction of the force that acts on the clothes in the spin cycle of a washing machine?
What exerts the force?
1.7 Represent and Reason
If a 40.0 g stone is whirled horizontally on the end of a 0.60 m string at a speed of 2.2 m/s, what
is the force the string exerts on the stone?
1.8 Represent and Reason
A bowling ball has a mass of 7.3 kg. If you move it around a circle with a radius of 0.75 m and a
velocity of 2.5 m/s, what force would you have to exert on it?
1.9 Represent and Reason
A 615 kg racing car completes one lap in 14.3 s around a circular track with a radius of 50 m.
The car moves at a constant speed.
a) What is the acceleration of the car?
b) What force must the track exert on the tires to produce this acceleration?