Download Centrip to post - Physics: 1(AE) 2(B,D)

Centripetal Motion
A. Centripetal Motion
Centripetal Motion is based on:
1. The path and motion of an object in a circle
2. The direction of the object is always changing
3. The velocity is never constant because the direction
is always changing
1. Velocity is a vector, so if its direction is always changing,
the velocity is always changing
2. The velocity of the object is always a tangent to the curve
4. The speed of an object will remain the same if the
radius of the circle remains the same
– The speed of the object is dependent on the size of the
circular path
5. In centripetal motion, there is no change in the
magnitude of the velocity or the speed, just a change
in direction of the object
B. Centripetal Acceleration
1. Every location along the circular path has an
acceleration
2. The acceleration at any point is always directed
towards the center of the circle
3. 𝑎𝑐 =
𝑣2
𝑟
ac = centripetal acceleration
v = velocity of the object
r= radius of the circle
1. 𝑎𝑐 =
𝑣2
𝑟
2. If we look at the relationships in this
equation:
3. If the speed of the object remains constant 
The greater the acceleration, the smaller the radius
 Why?
• A 1.5kg cart moves in a horizontal circular path of 1.3
meter radius at a constant speed of 2.0 meters per
second. Calculate the magnitude of the centripetal
acceleration of the cart
• A 2kg cart travels counter clockwise at a constant
speed of 6.0 meters per second in a horizontal circle
of radius 3 meters.
a. Calculate the magnitude and direction of the
centripetal acceleration of the cart
b. If the radius was doubled what would happen to
the acceleration?
Halved, doubled, quartered, quadrupled
c. If the speed was doubled what would happen to
the acceleration?
Halved, doubled, quartered, quadrupled
C. Centripetal Force
1. This is the force needed to keep an object moving
in a circle
2. Centripetal force is always directed towards the
center of the circular path
3. Equation: Fc=m x ac
Fc= centripetal force
m= mass in kg
ac= centripetal acceleration
4. Objects are always traveling at a constant speed,
meaning there is no net force acting on the object
5. ac and Fc are always directed inward and velocity is
always tangent to the curve of the circular path
Example:
• Determine the centripetal Force (Fc)
– A 1.5 kg cart moves in a horizontal circular path of
1.3 meter radius at a constant speed of 2.0 meters
per second.
Example: Equation Manipulation
• What is the magnitude of the centripetal force on the cart from
the previous slide? __________
• If the mass of the cart is doubled, what happens to the
centripetal force acting on the cart?
• If the speed of the cart is doubled, what happens to the
magnitude of the centripetal force of the on the cart?
• Which direction is the centripetal force of the cart acting?
• Which factor, when doubled, would produce the greatest change
in the magnitude of the centripetal force acting on the cart?