Ch. 8 slides.ppt Circular Motion.ppt

Ball on rope A child swings a 2 kg rock in a sling and swings it in a horizontal circle over her head. The horizontal circle has a radius of 1 meter. She swings the rock so that it completes three revolutions in 5 second (it completes one revolution in 1.67 s). What is the tension in the sling? Is the length of the string shorter, the same, or longer than 1 meter? Explain. What happens to a as th e speed is increased? Circular Motion.ppt

A highway curve of radius 100 m is banked at a 20° angle. Banked Curves A highway curve of radius 100 m is banked at a 20° angle. At what speed v0 can a car turn this curve without assistance from friction? What happens if the driver increases the speed of the car? Draw a free body diagram for this case. What is the maximum speed with which a car can travels this curve without slipping? Circular Motion.ppt

Roller Coaster Katie (mass = 45 kg) rides in a roller coaster that runs on a frictionless track. The track has a loop-the-loop of radius 10 m. The cart has a speed of 20 m/s at the top of the loop-the-loop and a speed of 35 m/s at the bottom. What is Katie's weight? What is Katie's apparent weight (normal force) at the top of the loop? What is Katie's apparent weight (normal force) at the bottom of the loop? If Katie isn’t wearing her seatbelt, what is the minimum speed the roller coaster can have that will allow Katie to stay in the car Circular Motion.ppt

Geosynchronous orbit A geosynchronous orbit stays above the same spot on the Earth during its orbit. This occurs for an orbit in the plane of the Earth's equator with a radius of approximately 42,164 km (26,199 mi) (measured from the center of the Earth). A satellite in such an orbit is at an altitude of approximately 35,786 km (22,236 mi) above mean sea level. Draw a free body diagram for a satellite, mass m, in geosynchronous orbit. What is the period, velocity and net force and acceleration of the satellite. Gravity is weaker this far from earth. What is the acceleration due to gravity here? Circular Motion.ppt

The fan A spider makes its home on top of a ceiling fan a 1/2 meter from the center of the fan. Bill Nye turns on the fan. The fan takes 2 seconds to go from rest to its final angular speed of 120 revolutions per minute. Amazingly, the spider moves with the fan without slipping. What is the final angular speed of the fan in SI units? What is the final speed of the spider? What is the angular acceleration (assuming that it's constant) of the fan during the first 2 seconds? What is the acceleration of the spider after 1 second? What is the angular displacement of the fan during the first 2 seconds? How far has the spider traveled?

Orbit The space shuttle travels around the earth at an altitude of of 400 km. Assuming that the gravitational force of the earth doesn't vary with distance (not a good assumption in general), how long does it take the shuttle to make one revolution around the earth? Rearth = 6378 km At 400 km, the actual weight of the space shuttle is 89% of its value on the earth’s surface. How long does it actually take the shuttle to make one revolution around the earth? Circular Motion.ppt