EWeaver+Lab+15+Centripetal+Force

Preliminary Questions 1. Explain why is circular motion at constant speed not a natural state of motion (according to Galileo). Circular motion at constant speed is not a natural state of motion because the object requires a net inward force acting on it from an outside body.

2. What do we formally call a change in motion per unit time and which of Newton's laws adequately expresses its relationship with a net force? Newton's second law says that the force is equal to the differential change in momentum per unit time.

3. What do you call a force that is directed towards the center of circular motion? A force that is directed towards the center of circular motion is the centripetal force.

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Analysis: The centripetal force needed to keep the object moving in a circle is supplied by the tension in the string which is caused by the mass, and the velocity. Centripetal force always points inwards, toward the center of the circle. Through this lab we found that if you increase the velocity of the stopper, the force needed to maintain the stopper's motion also increases. Also, if the speed of revolution is doubled, the centripetal force would be 4 times great because the centripetal force is directly related to velocity squared. When the velocity of the object increases, the centripetal force also increases.

Application: If a car were driving around a circular track, static friction would provide the centripetal force necessary for the car to go around the circle at constant speed. If the car was driving at a speed which required a centripetal force the road could not supply, it would cause the car to continue driving straight on its path and drive off the road. If the car doubled it's speed it would require four times the original centripetal force to complete the turn.