Name: ______________________________________ Date: ________________________
Gravity Pitch Gizmo
Vocabulary: escape velocity, gravity, orbit, trajectory, terminal velocity, parabola
Gizmo Warm-up:
1. Use the slider to set the Velocity to 0.0 km/s.
Click Play ( ).
A. What direction does the ball go? _______________
B. Sketch the pitcher and the trajectory of the ball (path
that the ball goes).
2. Click Reset ( ) and drag the pitcher to several new positions around Earth. Click Play
and watch the ball each time.
A. What do you notice? ________________________________________________
B. In what direction does gravity always pull the ball? _________________
C. Why do you think the ball always goes toward Earth? _______________
Get the Gizmo ready:
Activity A:
Click Reset.
How far does it
Drag the pitcher back to the top.
go?
Set the Velocity to 1.0 km/s (2,232 miles per hour).
1. Click Play and observe the ball’s trajectory (path). Draw a
simple sketch of the trajectory of the ball.
2. How would the trajectory of the ball change as the pitcher
throws it harder? Draw a sketch of what you think the
trajectory would look like if he threw the ball at a velocity of
5 km/s.
_______________________________________________
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3. Throw the ball at velocities shown in the table below. For
each throw, record the Distance traveled in the table.
Velocity Distance traveled
2.5 km/s
3.5 km/s
4.5 km/s
4. What happens with each throw?
_________________________________________________________________________
5. What force causes the ball to slow down and drop to the ground?
6. What conditions cause the planets to orbit in space without stopping?
7. Find the time it takes each of these planets to orbit the sun: Use internet
A. Mercury ____________
B. Venus _____________
C. Earth ______________
D. Mars ______________
E. Jupiter ____________
F. Pluto _____________
F. What do you notice about the orbit time compared to the distance from the sun?
7. Back to the Pitcher. Test 7 km/s and 8 km/s. Use the “–” zoom out control.
What happens?
A. What does the orbit look like for 7 km/s?
B. How is the orbit different at 8 km/s?
Get the Gizmo ready:
Activity B:
Click Reset.
Comparing
On the Planet menu, choose Venus.
planets
Set the Velocity to 1 km/s.
1. Look at the Planet mass and Planet radius of Venus. Compared to Earth, what are the
mass and radius of Venus? It will be a decimal. Look at the bottom of the animation.
Venus mass: _________ of Earth’s mass Venus radius: _________ of Earth’s radius
2019
2. Will the pitcher have to throw the ball faster or not as fast to send a ball into orbit around
Venus? _____________ Why? _________________________________________
3. Orbital velocity is the velocity needed to make a circular orbit. How fast does the pitcher
have to throw the ball to complete one orbit and it returns and hits him? It could be a
decimal so experiment with it.
A. What is the orbital velocity on Venus? _____________________________________
B. Do the same on Earth. What is the orbital velocity on Earth? ___________________
C. Based on this, which planet do you think has stronger gravity, Venus or Earth?
Explain ____________________________________________________________
4. Select Mars. Estimate what the orbital velocity will be on Mars: ________________
Why did you choose that value? _______________________________________________
5. Adjust the Velocity until you create a circular orbit on Mars and the ball returns to hit the
pitcher.
A. What is the orbital velocity on Mars? ______________________________________
B. How does gravity on Mars compare to Earth and Venus? _____________________
6. Extend your thinking: The escape velocity is the smallest velocity needed for the baseball
to escape from the planet’s gravity and fly off into space, never to return. When the ball
reaches escape velocity, the Distance traveled will read “infinity.”
A. Which planet do you think has the lowest escape velocity? ____________________
B. Use the Gizmo to test your prediction. Were you correct? _____________________
Get the Gizmo ready:
Activity C:
Click Reset.
Design a planet On the Planet menu, select Custom.
Set the Velocity to 7.0 km/s.
1. Set mass and radius to the positions in the table below and run play. Explain what happens
for each one.
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Planet mass Planet radius Velocity What happened?
0.0 1.0 7.0 km/s
1.0 1.0 7.0 km/s
2.0 1.0 7.0 km/s
2. How does increasing the mass affect the gravity of the planet?
_________________________________________________________________________
_________________________________________________________________________
3. Using what you have learned, create a planet with the strongest possible gravity. What are
the mass and radius of this planet? _____________________________________
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