For passenger comfort the centripetal acceleration on a railway curve must not exceed 1.5 m/s². What is the smallest radius rmin for a curve taken at 120 km/h?
Circular motion worksheet with answers
A 700 kg car drives around a flat curve of radius 80 m at a constant 9 m/s. Find the inward (centripetal) force Fc needed.
A car takes a flat curve of radius 95 m. The coefficient of static friction between tyres and road is 0.3. Use g = 9.81 m/s². Find the highest speed vmax at which the car can take the curve without skidding.
A small ball on a string of length 1.9 m moves in a horizontal circle so that the string makes a constant angle of 30° with the vertical (a conical pendulum). Use g = 9.81 m/s². Find the speed v of the ball.
A curve of radius 110 m is banked at 12°, 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 ball on a string 0.9 m long is swung in a vertical circle. Use g = 9.81 m/s². What is the smallest speed vmin at the top for which the string just stays tight?
Answer key
- 1. rmin = 740.7 m
- 2. Fc = 708.8 N
- 3. vmax = 16.72 m/s
- 4. v = 2.32 m/s
- 5. vmin = 10.91 m/s
- 6. vmin = 2.971 m/s
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