Free Fall Tower: An Exploration of Gravity and Design

Student Exploration: Free Fall Tower (gizmos) Patty climbs a tree. While sitting on a branch, she drops a leaf and an acorn at the same time. What would happen? The acorn would fall faster while the leaf will slowly drift downwards. But that would only be due to air resistance. Patty decides to try another experiment. From the same branch, Both the large, heavy rock and the small branch would fall at the she drops a large, heavy rock and a small pebble. What would same rate and hit the ground at the same time. happen this time? What did you drop? The ping pong ball and the watermelon. Did the objects fall at the same rate? No they didn't. Which object fell faster? The watermelon fell faster. Click Reset (). Drop each possible combination of objects without parachutes. Which object fell fastest? The watermelon Slowest? The ping pong ball. Why do you think some objects fall faster than others? Due to air resistance and the weight of the object. Form hypothesis: How do you think objects will fall when there is no air? All the objects will fall at the same rate. Experiment: Drop the different objects from the top of the tower. That both objects had the same speed and feel to the ground at What do you notice? the same time. Click Reset. Drop the watermelon and the ping pong ball from the top of the tower. Watch the speedometers. They show each object's speed in meters per second (m/s). What do you notice? Both objects fell at the same rate. What is the final speed of each object? 28.06 m/s An object is accelerating if its speed is changing. What can you say about the acceleration of objects falling in a vacuum? The objects are all accelerating but at the same rate. Interpret: Select the GRAPH tab. The graph shows the speeds of the objects over time. What do the lines on the graph look like? They are pointing upwards and are both on top of each other. What does that tell you? It tells me that the two objects had the same speed and time, even though their weight was different. Extend your thinking: In 1971, Apollo 15 commander Dave Scott Both objects would fall to the ground at the same time because dropped a hammer and a feather on the Moon, which has no air. there is no air on the moon. What do you think happened? Explain your answer. Observe: In Air, drop the objects from different levels of the tower. The heavier objects have a higher speed and fall to the ground Look carefully at the speedometers as the objects drop. What do faster than the smaller and lighter objects. you notice? Form hypothesis: When objects fall through the air, they are pushed by a force called air resistance. How do you think air resistance affects falling objects? Air resistance affects the movement of falling objects by slowing it down. What is the terminal velocity of the ping pong ball? The terminal velocity is 8.55 m/s. Select the GRAPH tab. How does the graph show terminal velocWhen the graph starts to go horizontal that's the terminal velocity. ity? Compare: Drop the soccer ball and the golf ball from the top of the tower. Which ball was slowed down more by air resistance? The soccer ball was more affected by air resistance. Extend your thinking: A soccer ball is heavier than a golf ball. Why Because it was larger and there was more air pushing up on the do you think the soccer ball fell more slowly than the golf ball? soccer ball then the golf ball. The higher the mass of an object the slower the object falls to the Make a claim about how the mass of an object affects how it falls ground. That's because there is more air resistance affecting the on Earth: object with the higher mass. Part A of the Gizmos shows how the watermelon, which has a Using information from Part A of your Gizmo provide evidence for larger mass, falls slower then the ping pong ball, which has a your claim: smaller mass. Air resistance affects how the object falls down. The higher the Make a claim about how air resistance affects how objects fall on mass of an object is the more air resistance encounters which Earth: slows down the speed of the object. 1/2 Using information from Part B of your Gizmo provide evidence for Part B of the Gizmos shows how air resistance affects the speed your claim: and the time of different objects. 2/2