Background: Isaac Newton gets credit for working out the Universal Law of Gravit
ID: 1441983 • Letter: B
Question
Background: Isaac Newton gets credit for working out the Universal Law of Gravity sometime around 1666. However, since the mass of the Earth was unknown in his time he was unable to write the complete Law of Gravity. He could not determine the proportionality constant G, also known as the Universal Gravitational Constant. To determine G the force of gravity between 2 objects of known mass must be measured. Since this force is extremely small, this is a very difficult experiment to do accurately. Henry Cavendish was the first to do so in 1798. Cavendish was trying to determine the average density of the entire Earth. He was dubbed “The man who weighed the Earth” after his experimental results were published. Other physicists then used his data to determine G and thus completed Newton’s work.
Purpose: You will obtain data about the force of gravity (Fg) between 2 objects of known mass just like Cavendish did. However, you will use a computer simulation instead of the complex and finicky torsion balance that Cavendish used. Using your data, your brain, and the analysis tool Graphical Analysis, you will determine the Law of Gravity including G and use it to determine the mass of the Earth.
Q1: We will be measuring Fg between 2 objects, m1 and m2 as shown below. If m1 has more mass than m2, how will Fg of m1 on m2 compare to Fg of m2 on m1?
Q2: The program initially shows Fg between a 38 kg m1 and a 25 kg m2. Does it verify your prediction from Q1? Change m1 to 25 kg and m2 to 38 kg. Make sure you always press Return or click on the white part of the screen after changing the masses. From the results describe in general the relationship between Fg of m1 on m2 and Fg of m2 on m1.
Explanation / Answer
Q1 )
Fg( of m1 no m2 ) = +Gm1 m2 /R^2
Fg ( of m2 on m1) = - Gm2 m1/R^2
both are same in magnitude but opposite in direction
Q2)
Fg = Gm1 m2 /R^2
even if we interchange the masses Fg will be same as it directly proportional to masses of both the bodies
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.