Centripetal Force Lab
What are the Characteristics of Circular Motion?
Purpose:
The purpose of this lab is to investigate the relationship between the speed of an object in uniform circular motion and its radius with a constant centripetal force.
Data:
Radius(m): you need at least 4 different Radii (5 would be better!)
Number of revolutions timed
Time for the revolutions
Mass of Stopper (constant)
Hanging Mass (constant)
Calculations:
Time for one Revolution: this is called the period, T
Force (the tension in the string)
Paper clip MUST
remain at the same
position.
Graph:
Period and Radius
(Which is independent and which is dependent?)
Write your mathematical model.
Errors:
What are the largest sources of errors in this lab and how do they effect your results?
Nov 9­3:02 PM
Nov 10­7:45 AM
What are the Characteristics of Circular Motion?
Velocity: constantly changing
direction
vi
vf
Period: time for one revolution
Radius:
Acceleration:
how tight the turn:
smaller radius => bigger
force
always directed toward
the center of the circle
Δv
vf - vi ⇒
vf
-vi
Nov 10­8:34 AM
Oct 31­12:02 PM
Circular Motion Formulas
vc =
ac =
2πr
T
4π2r
T2
=
v2
r
Fc = mac
Nov 1­9:46 AM
1. The Moon revolves around Earth in a circular orbit with a radius of 3.84x108 m. It takes 27.3 days for the Moon to complete one orbit around Earth. What is the centripetal acceleration of the Moon?
2. A clown rides a small car at a speed of 15 km/h along a circular path with a radius of 3.5 m.
a. What is the magnitude of the centripetal force on a 0.18­kg ball held by the clown?
b. At the point where the car is headed due north, the clown throws the ball vertically upward with a speed of 5.0 m/s relative to the moving car. To where must a second clown run to catch the ball the same distance above the ground as it was thrown?
3. A 0.45­kg ball is attached to the end of a cord of length 1.4 m. The ball is whirled in a circular path in a horizontal plane. The cord can withstand a maximum tension of 57.0 N before it breaks. What is the maximum speed the ball can have without the cord breaking?
4. A car moving at 12.67 m/s rounds a bend in the road. The bend is semicircular and has a radius of 60.0 m. What is the centripetal acceleration of the car?
5. A town has a large clock on the hall in the town square. The clock has hands that show the hours, minutes, and seconds. A fly is sitting on the tip of the hand that shows the seconds. If the length of the hand is 1.20 m, what is the fly’s centripetal acceleration?
Oct 31­12:15 PM
Circular Motion Guided Practice Answers
1.
2.
3.
4.
5.
6.
0.003 m/s2
0.89 N
13 m/s
2.7 m/s2
0.013 m/s2
2.5 m/s
6. A rock is tied to a string and spun in a horizontal circle. The string is 1.8 m long and the rock has an acceleration of 3.4 m/s2. What is the tangential velocity of the rock?
Nov 3­12:10 PM
Nov 1­7:33 AM
Homework :
Page 164: 36, 38
Page 166: 61, 62, 65, 66, 67
Nov 1­9:46 AM
Attachments
Projectile Motion Guided Practice.docx