Why is the centripetal force necessary for circular motion?
The centripetal force can be thought of as the force that causes circular motion.
When an object moves in a circle a force must always act on it, even when it moves at a constant speed. This is because velocity is a vector (and therefore has both a magnitude and a direction) and the direction the object is moving in is constantly changing.
This constant direction change is an acceleration, and we know from Newton's Second Law that any acceleration must have an force associated with it.
Similarly, the centripetal force must point towards the centre of the circle, and therefore perpendicular to the tangential velocity, to maintain the motion in the circle. If it did not exist the object would 'shoot off' in a direction tangential to the circle.
JB
Related Physics A Level answers
All answers ▸What is the difference between distance and displacement?
An engineering student found that the Youngs modulus of an alloy was 2.8 x 10^11 Pa. The 1.5m wire of the allow increased in length by 0.24% during an experiment. Calculate the stress on the wire.
A fluorescent light uses a lining to emit visible light, explain why this is necessary and how it works.
If a vehicle A, 1000kg moving at 5m/s collides with vehicle B, 750kg, moving in the opposite direction at 8m/s assuming no rebound what is the velocity of the vehicles after collision.