and Newton's 2nd Law: The Bowling Ball Drop
1. Determine the height of building using a dropped object.
2. Determine the free fall acceleration (gr) with air resistance using a FBD.
Materials: bowling ball, volleyball, nerf ball, other object, several stop watches
1. Sketch the free-body diagram (FBD) of a ball in free fall. Label the force of gravity (weight) and the air resistance vectors. Determine the masses of the three balls.
2. Drop the bowling ball from the height of the building (teacher does this!). Record the time of free fall with several stopwatches from the instant of release until impact. Drop the lowest and highest times, then find the average of the remaining times.
3. Repeat for a volleyball and for the Nerf Ball.
4. Repeat for another object if available.
Results, Analysis, and
1. Determine the height of the building using the bowling ball's time as the accepted value.
2. Calculate the velocity and momentum of the bowling ball upon impact. (p = mv)
3. Using the times for the volleyball and Nerf ball, calculate the acceleration rate for each. Now using the free-body diagram and the equilibrium expression, determine the air resistance for each ball. What are the units for air resistance?
4. Why did we use the bowling ball's time as the accepted value for finding the height?
5. Determine the ratio of the volleyball and Nerf balls' weight/air resistance. Can you draw any conclusion between this ratio and the rate of acceleration?
6. If the balls were thrown upward, what would you predict for the rate of acceleration?
7. Define terminal velocity. What can you say about the rate of acceleration for an object that reaches terminal velocity? Give two examples. Carefully sketch a FBD showing the forces on an object that has reached terminal velocity.
8. On the moon, gravity is 1.62 m/s2. If this entire experiment were performed on the moon, how much time would it take for the bowling ball to reach the lunar surface? The volleyball? The Nerf Ball? What would be their velocities upon impact?
9. Sketch a FBD of a Nerf ball falling with a wind out of the west. Show the approximate resultant force.
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