Uniform Circular Motion

Answer Me!!!! Newton’s Laws state that an object in

motion will stay at the same velocity until acted upon by an unbalanced force. What will happen when a force is

directed perpendicular to the line of motion?

Uniform Circular Motion The motion of an object at a constant

speed in a circular path is call Circular Motion.

Centripetal Forceis directed towardthe center of the circle. This causesthe object to accelerateinward toward the center.

Fc

v

ac

Centripetal Acceleration Centripetal Acceleration (ac) is the

acceleration of an object causing the object to change direction along a circular path.

The equation that determines centripetal acceleration is:

v= velocity r= radius

r

vac

2

Centripetal Force Using the equation:

Applying the centripetal acceleration:

maF

r

mv

r

vmmaF cc

22

Practice Problem 1 A 2000 kg car travels at a constant speed

of 12 m/s around a circular curve of radius 30 m. What is the magnitude of the centripetal

acceleration of the car? As the car goes around the curve, in which

direction is the centripetal force directed?

Practice Problem 2 An athlete in a hammer-throw event

throws a 7kg hammer in a horizontal circle at a constant speed of 12 m/s. The radius of the hammer’s path is 2 m. If the hammer is released, which direction will the hammer go? Straight Ahead Toward the center of the circle Along the Circular path

Practice Problem 3 A 1.5 kg cart travels in a horizontal circle

of radius 2.4 m at a constant speed of 4.0 m/s. Draw a diagram of this motion and label the velocity, acceleration and force acting on the cart.

Practice Problem 4 A 60kg car travels clockwise in a

horizontal circle of radius 10m at 5.0m/s. What is the magnitude of the centripetal force?

Practice Problem 5 A child is riding on a merry-go-round. As

the speed of the merry-go-round is doubled, what happens to the magnitude of the centripetal force acting on the child?

Answer Me!!! A 600kg race car travels at a constant

speed along a circular race track. If it takes 36 seconds to complete one lap and the radius of the track is 160m. Calculate the speed of the car.