Syllabus Edition
First teaching 2020
Last exams 2024
|
12.2.3 Calculating Centripetal Force
Calculating Centripetal Force
- An object moving in a circle is not in equilibrium, it has a resultant force acting upon it
- This is known as the centripetal force and is what keeps the object moving in a circle
- The centripetal force (F) is defined as:
The resultant force towards the centre of the circle required to keep a body in uniform circular motion. It is always directed towards the centre of the body's rotation.
- Centripetal force can be calculated using:
Centripetal force is always perpendicular to the direction of travel
- Where:
- F = centripetal force (N)
- v = linear velocity (m s-1)
- ⍵ = angular speed (rad s-1)
- r = radius of the orbit (m)
- Note: centripetal force and centripetal acceleration act in the same direction
- This is due to Newton’s Second Law
- The centripetal force is not a separate force of its own
- It can be any type of force, depending on the situation, which keeps an object moving in a circular path
Examples of centripetal force
Worked example
A bucket of mass 8.0 kg is filled with water is attached to a string of length 0.5 m. What is the minimum speed the bucket must have at the top of the circle so no water spills out?
Step 1: Draw the forces on the bucket at the top
Step 2: Calculate the centripetal force
-
- The weight of the bucket = mg
- This is equal to the centripetal force since it is directed towards the centre of the circle
Step 3: Rearrange for velocity v
-
- m cancels from both sides
Step 4: Substitute in values
You've read 0 of your 0 free revision notes
Get unlimited access
to absolutely everything:
- Downloadable PDFs
- Unlimited Revision Notes
- Topic Questions
- Past Papers
- Model Answers
- Videos (Maths and Science)
Did this page help you?