A small object sits 15 cm from the axis of a disc that turns at a steady 78 revolutions per minute. Find the speed v of the object.
Circular motion worksheet with answers
An 800 kg car drives around a flat curve of radius 40 m at a constant 9 m/s. Find the inward (centripetal) force Fc needed.
A car takes a flat curve of radius 70 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.
In a fairground rotor, riders stand against the wall of a vertical cylinder of radius 3.3 m. When it spins fast enough the floor drops away and friction holds them up. The coefficient of static friction is 0.8. Use g = 9.81 m/s². Find the smallest rotation rate n in revolutions per minute.
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?
A 1.8 kg ball on a string 1 m long is swung in a vertical circle. At the lowest point it moves at 3 m/s. Use g = 9.81 m/s². Find the tension T in the string at the lowest point.
Answer key
- 1. v = 1.225 m/s
- 2. Fc = 1620 N
- 3. vmax = 14.35 m/s
- 4. n = 18.41 rpm
- 5. vmin = 2.971 m/s
- 6. T = 33.86 N
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