- #1
gsingh2011
- 115
- 1
For a body to undergo uniform circular motion, a centripetal force which is perpendicular to the velocity at all times must be applied to the body. For the moon and the earth, the gravitational force exerted on the moon by the Earth causes the moon to move in a circle instead of continue on a straight path. A similar example is a ball on a string. When the ball is moving in a circle parallel to the ground, the centripetal acceleration is caused by the tension in the string. So what causes the centripetal acceleration of a person on the earth? The reason I'm confused is because the force of gravity on a person is exactly canceled out by the normal force. If it wasn't, then that person would either move up or move down. So if those two forces cancel out, what is the force perpendicular to our velocity that keeps us moving in a circle?