Circular Movement: centripetal or centrifugal force? (Prepositions of Movement Part I)

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Circular Movement: centripetal or centrifugal force?


Car accidents often happen when a car is travelling around a corner too fast. The car can go off the road and crash into something. People usually think this is the result of centrifugal force, but is it?

According to Newton's first law of motion, a moving object will travel along a straight path unless an outside forece acts on it. So, to move in a circle, an object needs a constant force pushing it towards the centre. This is centripetal (or 'centre-seeking') force.

If you swing a ball on the end of a string above your head, you can feel the string pulling away from you. This is the centrifugal force. However, the force which the string applies to the balls is centripetal. If the string breaks, the ball will fly off. Without a centripetal force to pull the ball into the centre of the circle, it continues in a straight line.

In a car around a bend, the centripetal force is the sideways friction between the tyres and the road surface, If the car goes too fast, it goes off the road because the fruction is not strong ennough to provide the necessary centripetal force to keep it on the road.


1. Which is the use of the different prepositions that appear in the previous text?





2. In some of the following sentences the preposition of movement is wrong. If it is wrong you have to correct it.

  • She walked into the room and said hello
  • The dog jumped onto the river.
  • We walked to the mountain for an hour, but turned north before we reached it.
  • We couldn't find the shop and walked past the centre for hours looking for it.
  • The cat jumped off the table and ate my steak.




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