A ball is fastened to a string and is swung in a vertical circle. When the ball is at the highest point of the circle the tension in the string is: ? a. mg c. ma - mg b. mg + ma d. mg/ma

Q7

3. A roller coaster is built so that there is a circular curve of radius 80.0 m at the top of one hill. The speed with which the car goes over the hill varies. Assume the passenger has a mass of 50.0 kg. The cars have wheels over and under the track so that it stays on and the passenger is wearing a seatbelt. a. If the speed is 20.0 m/s going over the top what is the force on the passenger? Force factor? Is the force from the seat or the belt?

A curve in a stretch of highway has radius 512 m. The road is unbanked. The coefficient of static friction between the tires and road is 0.600. a. What is the maximum safe speed that a car can travel around the curve without skidding?  answer in m/s b. Which of the following is the correct free-body diagram of the car when it enters the curve at a speed greater than the maximum safe speed? (OPTIONS ATTACHED) c. When the car enters the curve at a speed greater than the maximum safe speed (speed at which the car won’t skid), which of the following statements are correct?  The static frictional force is not large enough to keep the car in a circular path. The car skids toward the outside of the curve. The car skids toward the inside of the curve. The static frictional force is large enough to keep the car in a circular path.