Blackburn, The pendulum: a case study in physics (Oxford University Press, Oxford, 2005). The main advantages of this experiment are its simplicity, low cost and wealth of both physical and mathematical concepts.įrom the theoretical physics point of view, the physical pendulum can be used to understand the behavior of systems acted on restoring forces proportional to the displacement from the equilibrium point, the concept of a rigid body and the determination of its center of mass (CM) and moment of inertia (and the radius of gyration), the use of Steiner's theorem, the effect of damping, among others G.L. Brittle, Physics Education 47, 537 (2012).], which is generally used to get a measurement of the gravitational acceleration g. Weltin, American Journal of Physics 32, 267 (1964). Check it out!Ī feather and a hammer were dropped at the same time on the moon.The analysis of the oscillatory behaviour of physical systems is a fundamental part of physics courses at the undergraduate level, where simple harmonic oscillators are studied, both from the theoretical and the experimental point of view.Ī very common experiment in fundamental physics courses, which has been used throughout the years, consists on the analysis of the oscillatory motion of a physical pendulum H. The Brainiacs dropped cars to test Galileo's ideas about falling objects. How is the force of gravity on an object related to gravitational acceleration? If the mass of a falling object doesn't affect its motion, why does a feather fall slower that the g ball? Why did you have to be careful to throw the ball horizontally? What would have happened if you accidentally gave the ball a slightly upward initial velocity? What about a slightly negative initial velocity? Finally, if you saw that all objects fall at the same rate, you have verified Galileo's experiment – just like he supposed did at the Tower of Pisa. Did you discovered that regardless of the speed you threw the ball horizontally the time of the fall was the same? If so, you have shown that the horizontal motion does not affect the vertical motion. If you found that the time for the fall was about 0.45s, then you have verified the accepted value of the acceleration due to gravity is 9.8m/s 2. Comment on your results compared with your prediction.Repeat this several times until you are sure which one hits the ground first.Drop a G-ball and a baseball from the same height at the same time.Do the values vary more than they did for the dropped G-ball? Comment on your results and compare them with your prediction.Repeat this tossing the ball horizontally at several different speeds.Time the fall for the G-ball tossed horizontally from a height of 1.0m.Comment on your value compared with your prediction.Repeat this process several times to get an average value.Following the instructions packaged with the G-ball, use it to time a fall of 1.0m.If you drop a G-ball and a baseball/softball at the same time which one will hit the ground first? Again, take a moment to write down your thinking to explain your answer. Take a moment to write down your thinking and explain your answer. The time for the fall will decrease if the G-ball is thrown faster.The time for the fall will stay the same if the G-ball is thrown faster.The time for the fall will increase if the G-ball is thrown faster.If you toss the G-ball horizontally, at different speeds do you think: Use the accepted value of g = 9.8m/s 2 and the kinematic equation to predict the time of fall. Finally, you will drop the G-ball and a baseball to see which object accelerates more rapidly.Īssume that you drop the G-ball from rest from an initial height of 1.0m. Next, you'll throw the G-ball horizontally at different speed and see if the time of fall changes. You need a G-Ball, a meter stick, and other objects to drop such as a baseball/softball.įirst, you will measure the acceleration due to gravity by simply dropping the G-ball and getting the time to fall. Using the G-Ball by Arbor Scientific, you can measure this value and compare the acceleration of other objects with different masses and in different states of motion. Modern measurements indicate that this gravitational acceleration is about 9.81m/s 2. Galileo claimed that all objects fall toward Earth with the same acceleration.
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