Newton's Law of Universal Gravitation
Source: Ketron Mitchell-Wynne, PhD, Asantha Cooray, PhD, Department of Physics & Astronomy, School of Physical Sciences, University of California, Irvine, CA
Legend states that Isaac Newton saw an apple fall from a tree. He noticed the acceleration of the apple and deduced that there must have been a force acting upon the apple. He then surmised that if gravity can act at the top of the tree, it can also act at even larger distances. He observed the motion of the moon and the orbits of the planets and eventually formulated the universal law of gravitation. The law states that every particle in the universe attracts every other particle with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them. This force acts along the line joining the two particles.
Gravitational acceleration g, which is the acceleration an object on the surface of the Earth experiences due to the Earth's gravitational force, will be measured in this lab. Accurately knowing this value is extremely important, as it describes the magnitude of the gravitational force on an object at the surface of the Earth.
1. Measure the acceleration of gravity at the Earth's surface.
- Obtain a ball, a meter stick, two timing gates, and three clamps.
- Use one clamp to attach the meter stick to a table or another sturdy surface slightly off the ground.
- Use the other two clamps to connect the timing gates to the top and bottom of the meter stick. Make sure that each sensor is lined up with the end of the meter stick. This way, d is known to be 1 m in Equation 6.
- Once it has been ve
The value of g measured from the experimental procedure is shown in Table 1. The freefall time from step 1.4 is recorded in the first column of Table 1. The measured value of g is then calculated using Equation 6. The accuracy of this value can be checked by comparing it to the value of g calculated from Equation 3 using the following values: G = 6.67 x 10-11 m3kg<
The branch of mechanics that is concerned with the analysis of forces on objects that do not move is called statics. Engineers who construct building and bridges use statics to analyze the loads on the structures. The equation F = mg is used throughout this field, so an accurate measurement of g is extremely important in this case. Newton's law of universal gravitation is used by NASA to explore the solar system. When they send probes to Mars and beyond, they use the universal law o
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