A car moves around a track at constant speed.
When is the centripetal force the greatest? CD or AB

 

 

 

 

 

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

 

 

 

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 ]

 

Cut the Rope

LINK

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

 

 

 

 

Great Centripetal Force Demo

Show Me The Physics YouTube Channel

 

 

 

 

 

E. Changing Centripetal Force

 

1. Fc and Mass?

Put your mouse over each variable above

[ Flash ]

 

 

 

 

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?

[ Flash ]

 

 

 

 

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

 

 

 

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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