1-8 Centripetal force

• Natuurkunde
• Middelbare school
• vwo
• Leerjaar 3

Centripetal force

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- Pen and pencil

- Calculator

- iPad

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Schoolbags in

the cupboard

Phones in the phonebag

Lesson goals:

• Calculate the centripetal force with the formula:

• Calculate mass, velocity and  

       radius with the same formula

F​cpf​​=​r​​m⋅v​2​​​​

Centripetal force

• For an object to move in a circular motion a centripetal force is needed.
• This force is always directed to the centre of the circle.
• The size of the force you can calculate with the formula:

F​cpf​​=​r​​m⋅v​2​​​​

     = centripetal force (N)

m = mass (kg)

v = velocity (m/s)

r = radius (m)

F​cpf​​

Example: 

A satellite of 720 kg circulates the earth above the radius with a velocity of 

27 000 km/h. The satellite is at a height of 680 km above the earth. The radius of the earth at the equator is 6370 km. Calculate the gravitational force with which the earth attracts the satellite. 

Define problem:

Calcualtion: 

therefore

Try by yourself

Which force is the centripetal force in the following situations:

a) A chair goes round and round in a mery-go-round.

b) A car drives through a bend.

c) The moon 'Europe' circulates Jupiter.

a) The cable that attaches the chair to the mery-go-round.

b) The friction between the tyres of the car and the road surface.

c) The gravitational force between Jupiter and its moon 'Europe'.

Try the following

A satellite (m = 2100 kg) circles the earth in 6 hours. The height of the satellite above the earths surface is 10 400 km. The radius of the earth is 6371 km.

a) Calculate the distance from the satellite to the centre of the earth.

b) Calculate the velocity of the satellite.

c) Calculate the centripetal force on the satellite.

The length of a complete rotation around the earth is

The time for one rotation is

The average velocity is:

What did you
learn today?

Now try

The test yourself of paragraph 1.3

And of the open questions 33, 34, 35

F​mpz​​=​r​​m⋅v​2​​​​