Please write neatly if handwritten, thanks. In class we watched a video demonstr
ID: 1653384 • Letter: P
Question
Please write neatly if handwritten, thanks.
In class we watched a video demonstrating an attraction between a large and small sphere. A single frame of the video is reproduced here. It was postulated in class that the force of attraction being witnessed here is much too strong to be a gravitational attraction. We named this much stronger force the electric force. This postulate, and the resulting need to introduce a new force, can be backed up with some numbers. That's the goal of this problem. Provide answers to the following three questions: Calculate the magnitude of the attractive gravitational force that the large sphere exerts on the small sphere. Use the symbol F_gravity for the magnitude of this force. Calculate the actual force that the large sphere exerts on the small sphere to pull it away from vertical by the angle shown in the diagram. Use the symbol F_actual for the magnitude of this force. Draw a conclusion: is the actual force much too large to be due to gravitational attraction? Answer YES or NO and then support your conclusion by referring to the results of your calculations. All of the physics needed to complete these calculations you learned in first-semester college physics (so you won't find any help in Chapter 21). But you will need some numbers to arrive at quantitative results. It might be helpful to know that the mass and radius of the large sphere are M = 150g and R = 10.0 cm, respectively. The mass and radius of the small sphere are m = 0.0500 g and r = 0.500 cm, respectively. Any other quantities needed can be estimated from the picture and fundamental constants can be found in your textbook.Explanation / Answer
Fgravity = GMm / d2
Given G = 6.673 x 10-11 Nm2/Kg2
M = 0.15 Kg
m = 0.05 x 10-3 Kg
d = 10 cm = 0.1 m (from the figure)
(1) Fgravity = [ 6.673 x 10-11 x 0.15 x0.05 x 10-3 ] / [0.1 x 0.1]
Fgravity = 5 x 10-14 N
(2) Angle thread makes with the vertical = 100
The resultant of Factual and W = mg shold be at 100 to the vertical (equal and opposite to tension)
( Factual) / (mg) = tan (100) or Factual = mg tan(100)
Factual = 8.64 x 10-5 N
(3) No, The force is very small due to gravitational attraction.