A small object sits 5 cm from the axis of a disc that turns at a steady 30 revolutions per minute. Find its centripetal acceleration ac.
Circular motion worksheet with answers
For passenger comfort the centripetal acceleration on a railway curve must not exceed 2 m/s². What is the smallest radius rmin for a curve taken at 300 km/h?
A small ball on a string of length 0.5 m moves in a horizontal circle so that the string makes a constant angle of 45° with the vertical (a conical pendulum). Use g = 9.81 m/s². Find the time T for one revolution.
In a fairground rotor, riders stand against the wall of a vertical cylinder of radius 2 m. When it spins fast enough the floor drops away and friction holds them up. The coefficient of static friction is 0.3. Use g = 9.81 m/s². Find the smallest rotation rate n in revolutions per minute.
A curve of radius 290 m is banked at 15°, and the coefficient of static friction between tyres and road is 0.1. Use g = 9.81 m/s². Find the lowest speed vmin at which a car can take the curve without sliding down the bank.
A curve of radius 250 m is banked at 30°, and the coefficient of static friction between tyres and road is 0.4. Use g = 9.81 m/s². Find the highest speed vmax at which a car can take the curve without sliding up and out.
Answer key
- 1. ac = 0.4935 m/s²
- 2. rmin = 3472 m
- 3. T = 1.193 s
- 4. n = 38.61 rpm
- 5. vmin = 21.57 m/s
- 6. vmax = 55.83 m/s
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