Drop and downward throw of a ball: Quantitative Testing Experiment
Aim
To test two models: (a)an object carries a force that another object exerted on it when it pushed it and the force dies out gradually, the object's velocity is proportional to the sum of all forces exerted on it; (b) an object does not carry a force that another object exerted on it when it pushed it, the object's acceleration is proportional to the sum of all forces exerted on it.
Prior Knowledge
Graphing skills.
Obtaining acceleration from a position-versus-time graph or veocity-versus-time graph.
Description of the Experiment
First, an object is dropped from a certain height, then the same object is thrown down from the same height.
Predict qualitatviely the shape and slope of the velocity-versus-time graphs and acceleration-versus-time graphs that you should obtain from the motion data according to both models.Justify your prediction.
Observe the experiment, collect the data, represent the data with the velocity-versus-time graphs and decide whether your prediction was confirmed.
Decide which model is more productive.
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If you want to download the movie to your computer, right-click or control-click
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Questions
Did the objects fall with constant speeds?
Did the objects fall with constant accelerations? If they fell with constant acceleration each, were their acceleration different or the same?
Which model explains the results of the experiments better?
Why did the second object reach the ground faster? How is this fact explained by the second model? Use your knowledge of kinematics to help.
