Science Homework Help

1. A car travels at a constant speed around a circular track whose radius is 3.69 km. The car goes once around the track in 356 s. What is the magnitude of the centripetal acceleration of the car?

2. A centrifuge is a device in which a small container of material is rotated at a high speed on a circular path. Such a device is used in medical laboratories, for instance, to cause the more dense red blood cells to settle through the less dense blood serum and collect at the bottom of the container. Suppose the centripetal acceleration of the sample is 6.95 x 103 times as large as the acceleration due to gravity. How many revolutions per minute is the sample making, if it is located at a radius of 6.91 cm from the axis of rotation?

3.At an amusement park there is a ride in which cylindrically shaped chambers spin around a central axis. People sit in seats facing the axis, their backs against the outer wall. At one instant the outer wall moves at a speed of 3.43 m/s, and an 62.9-kg person feels a 385-N force pressing against his back. What is the radius of a chamber?

4.A 980-kg race car can drive around an unbanked turn at a maximum speed of 44 m/s without slipping. The turn has a radius of 120 m. Air flowing over the car’s wing exerts a downward-pointing force (called the downforce) of 9400 N on the car. (a) What is the coefficient of static friction between the track and the car’s tires? (b) What would be the maximum speed if no downforce acted on the car?