Pre-Lab Questions
1. State the inverse square law in your own words.
The inverse square law is used to describe the distance between two objects based
... [Show More] on the force
of gravity between them and their fixed positions.
2. State the equation used to find the average velocity of an object traveling in uniform circular
motion.
v = 2πr/T
3. Consider an object in orbit around the earth, such as a man made spacecraft or the moon. Are
these objects accelerating?
Yes because the further away the moon moves from the earth the more acceleration it has
otherwise gravitational pull will affect the acceleration of the moon if it moves closer to the
Earth.
Lab 5 Circular Motion & Gravity PHY250L
EXPERIMENT 1: BALANCING CENTRIPETAL FORCE
Introduction Questions
1. Suppose an object rotates 15 times every 2 seconds. State the equation for the period of an
object in circular motion in variable form, then calculate the period of rotation, ensuring you
include the correct units. You must show your work for credit.
Step 1: T=1/f Step 2: T=15rotations/2sec Step 3: T=7.5rotations per second
2. In this lab, you will be rotating a mass on one side of a string that is balanced by a second mass
on the other end of the string (Figure 5). If you apply Newton's Second Law of Motion to mass 1,
m1, and mass 2, m2, you can solve for the period of mass 1, which is
P=√
π
2
r
g
/Below, derive this equation by using Newton’s Second Law. You must show all pertinent algebra
and mathematical steps for credit. Hint: assume m1= 4m2. How is the centripetal force on m1
related to the force of gravity on m2?
F=ma, ac=rv^2, Fc=m1/rv^2, Fg=m2g, M1=4m2, Fc=Fg, 4m2/v^2*r=m2g, 4/v^2*r=g, P=3.14^2r/g
Lab 5 Circular Motion & Gravity PHY250L
Data and Observations
Input the time it took to conduct 15 revolutions and the corresponding period into the table below.
Then use the equation in Question 2 of the experiment introduction to calculate the expected value of
the period of rotation. In the final column, calculate a percent error between these two values.
Table 1. Rotational Data
Radius (m) Time per 15
revolutions (s) Period (s) Expected
Value
Percent
Error (%)
0.25 11.47sec 0.76s 0.7646 0.61%
0.40 12.85sec 0.86s 0.8566 0.40%
0.15 7.10sec 0.47s 0.4733 0.70%
Insert a photo of the apparatus you built for this experiment. The photo must clearly depict the correct
number of washers and a length of line that is reasonable for the radius you denoted in the above table.
Your photo must also include your handwritten name. Submissions that do not contain a photo with
these requirements will be rejected. [Show Less]