A car moving in a circle is
always turning in the same direction

Penn State Schuylkill

Go Nittany Lions!!

 

 

 

Identify the Fc and v.
What is the relationship between Fc and v?

[ Flash ]

 

 

 

 

D. Centripetal Force (Fc) - force directed toward center of circle which keeps an object moving in a uniform circular path

 

 

Fc  =   mac = mv2
r

 

 

AP Physics p. 130) 8, 11

Ex) A 5.0 kg object moves in a circle at a constant speed of 10. m/s. What is the radius of the object's circular path if the object's centripetal force is 1000. N?

 

 

 

 

 

 

 

 

Ex) A 5.0 kg object moves in a circle at a constant speed of 10. m/s. What is the radius of the object's circular path if the object's centripetal force is 1000. Newtons?

 

 

Fc = mv 2
r  

 


  1000. N =  5.0 kg(10. m/s)2
r

 

 

(1000.) = 500/r

 

 

1000r = 500

 

r = 500/(1000)

 

 

r = .50 meters

 

 

 

Image created by John Wetzel, founding author of WikiPremed.
Released under a Creative Commons Attribution 3.0 License.
 

WikiPremed Kinematics Image Archive

 

 

 

 

Show Me The Physics YouTube Channel

 

 

 

 

 

E. Changing Centripetal Force

 

1. Fc and Mass?

Put your mouse over each variable above

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Direct Relationship

(Both variables on top)

 

Mass Fc
x 2



x 2

x 3



x 3
x 4







x 4
x 1/2







x 1/2
x 1/4



x 1/4

 

 

2. Fc & Radius?

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Inverse Relationship

(One variable on top,
other on bottom)

 

Fc r
 



x 1/2
x 2


 



x 1/3
x 3


 



 

x 1/4
x 4




x 2
 x 1/2





x 4
 x 1/4

 

 

A car moves around a track at constant speed.
When is the acceleration greatest?

What is the acceleration from A to D?

 

 

 

 

 

 

 

a is greatest from A to B. r is small.

 

 

 

3. Fc & Velocity?

[ Flash ]

 

 

 

 

Direct Square Relationship

 

 

 

(Both variables on top, one is squared)

 

 

 

 

V Fc
x 2






x 4

x 3




x 9
x 4






x 16
x 1/2








x 1/4
x 1/4





x1/16

 

 

 

 

2 Step Challenge

Ex) A toy car moves in a circular track of radius 5.00 m in 10.0 seconds.

What is the car's centripetal acceleration?

 

 

 

 

 

ac = V2/r

 

 

 

r = 5.00 m

t = 10.0 sec

a = ?

 

 

 

Need to first find V!!!

V = Dd/Dt

 

 

 

 

V = (2∏r)/t

 

 

 

 

= [2∏(5.00 m)]
(10.0 sec)

 



V = 3.14 m/s

 

 

ac = V2/r

 

 

ac = (3.14 m/s)2 /(5.00 m)

 

 

ac = 1.97 m/s2

 

 

 

 

 

 

[ Flash ]

Hammer Throw

 

 

 

 

 

 

 

Teaching from Space: Centripetal Force

This media asset is adapted from video provided by NASA's Teaching From Space program. 
Produced bt WNET.org

http://www.teachersdomain.org/resource/npe11.sci.phys.maf.centripetal/

 

 

 

 

Satellite
Motion

 

 

 

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