2.5 Centripetal Forces

Physics Essential Standards Covered:

Phy.1.2.5

Recognize the cause and effect relationship between centripetal force and the change in velocity due to change in direction (centripetal acceleration) of an object as an example of Newton’s second law;
Recognize that a centripetal force is not the result of circular motion but is provided by interaction with another object.

Key Vocabulary

Centripetal Force
Centripetal Acceleration
Circular Path
Radius
Velocity

Essential Question: What is centripetal force, why is it important, and how is it calculated?

Lesson:

Centripetal Force: is the force necessary to pull and object into circular motion.

Remember Newton's 2nd Law:

F = ma

In order to get an object to move in circular motion we must apply a Force and a circular acceleration. We must accelerate the object in a circular path in order to have a centripetal force.

Remember the centripetal or circular acceleration equation:

The centripetal acceleration is dependent on the velocity vector and the radius of the circle.

Remember the force points towards the center of the circular path of motion. We can substitute our centripetal acceleration equation into our Newton's 2nd law equation and end up with the centripetal force:

Fun Facts:

The further away you are from the center of a merry go round, the more force you will feel.
If you are in the center of a merry go round you will experience no centripetal force.
This type of physics is what makes fairs, playgrounds, and amusement parks fun!
Also the fatter you are the more centripetal force you will feel. Ha!
This is also why ice skaters when performing a triple axel pull their arms in close because it decreases the radius of their turn and increases their centripetal acceleration allowing them to spin faster.

Let's do our own testing of this theory! I need to borrow a student good at balancing)

Get on the scale with the bottles of alcohol and find your mass.
Stand on the ground with your arms straight out. Another volunteer is going to use a meter stick to measure the radius/arm span from the middle of back to her the outside of hand.
Now we are going to calculate the circumference of circular motion.
Student stand on the Lazy Susan and two volunteers push in a circle. Here's the tricky part: Someone time how long it take to make one full rotation.
Now we are going to calculate circular speed or velocity.
Now let's find her centripetal force.
Now let's pull arms in and measure the radius with a meter stick from the center of back to the edge of shoulders.
Let's calculate new circumference.
Now get's back on the Lazy Susan with arms all the way extended. Two volunteers will push again to start circular motion. After 2 seconds bring arms all the way in and volunteer will time how long it takes to make one revolution.
Let's calculate the new velocity and centripetal force.
How did the force change when brought arms inward? Why did it change?

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2.5 Centripetal Forces

Physics Essential Standards Covered:

Key Vocabulary

Centripetal Force

Centripetal Acceleration

Circular Path

Radius

Velocity

Essential Question: What is centripetal force, why is it important, and how is it calculated?

Lesson:

Centripetal Force: is the force necessary to pull and object into circular motion.

Remember Newton's 2nd Law:

F = ma

In order to get an object to move in circular motion we must apply a Force and a circular acceleration. We must accelerate the object in a circular path in order to have a centripetal force.

Remember the centripetal or circular acceleration equation:

The centripetal acceleration is dependent on the velocity vector and the radius of the circle.

Remember the force points towards the center of the circular path of motion. We can substitute our centripetal acceleration equation into our Newton's 2nd law equation and end up with the centripetal force:

Fun Facts:

The further away you are from the center of a merry go round, the more force you will feel.

If you are in the center of a merry go round you will experience no centripetal force.

This type of physics is what makes fairs, playgrounds, and amusement parks fun!

Also the fatter you are the more centripetal force you will feel. Ha!

This is also why ice skaters when performing a triple axel pull their arms in close because it decreases the radius of their turn and increases their centripetal acceleration allowing them to spin faster.

Let's do our own testing of this theory! I need to borrow a student good at balancing)

Get on the scale with the bottles of alcohol and find your mass.

Stand on the ground with your arms straight out. Another volunteer is going to use a meter stick to measure the radius/arm span from the middle of back to her the outside of hand.

Now we are going to calculate the circumference of circular motion.

Student stand on the Lazy Susan and two volunteers push in a circle. Here's the tricky part: Someone time how long it take to make one full rotation.

Now we are going to calculate circular speed or velocity.

Now let's find her centripetal force.

Now let's pull arms in and measure the radius with a meter stick from the center of back to the edge of shoulders.

Let's calculate new circumference.

Now get's back on the Lazy Susan with arms all the way extended. Two volunteers will push again to start circular motion. After 2 seconds bring arms all the way in and volunteer will time how long it takes to make one revolution.

Let's calculate the new velocity and centripetal force.

How did the force change when brought arms inward? Why did it change?