Circular Motion – Numerical Problems (Class 11
Physics)
1. A body of mass 0.2 kg is whirled in a horizontal circle of radius 0.5 m by a string inclined at 30° to
the vertical. Find: (i) tension in the string (ii) speed of the mass. Answer: T = 2.3 N, v = 1.7 m/s.
2. A bob of mass 200 g is whirled in a horizontal circle of radius 50 cm by a string inclined at 30° to
the vertical. Find the tension in the string and the speed of the bob. Answer: T = 2.3 N, v = 1.7 m/s.
3. An object of mass 0.5 kg is rotated in a horizontal circle by a string of length 1 m. The maximum
tension before the string breaks is 50 N. Find the greatest number of revolutions per second.
Answer: 1.6 rev/s.
4. A stone of mass 0.8 kg is attached to a string 0.9 m long. The string breaks if tension exceeds
600 N. Find the maximum speed without breaking the string. Answer: 0.85 rev/s.
5. An object of mass 4 kg moves in a vertical circle of radius 1 m with constant speed 3 m/s. Find
the maximum tension in the string. Answer: 76 N.
6. A mass of 0.2 kg moves in a vertical circle of radius 1 m with constant speed. The minimum
tension is 3 N. Find the speed and maximum tension. Answer: v = 5 m/s, Tmax = 7 N.
7. At what angle should a road be banked so that a car moving at 50 km/h can turn safely on a
circular road of radius 200 m? Answer: 5.5°.
8. A mass of 1 kg is attached to a string 1 m long and moves in a horizontal circle of radius 60 cm.
Find the tension and period of motion. Answer: T = 12.5 N, Period = 1.77 s.
9. A string breaks when a force of 25 N acts on it. A mass of 500 g attached to a 1 m string is
rotated in a horizontal circle. Find the maximum revolutions per minute without breaking the string.
Answer: 67.5 rpm.
10. An object of mass 8 kg moves in a vertical circle of radius 2 m with constant speed 6 m/s. Find
maximum and minimum tension. Answer: Tmax = 224 N, Tmin = 64 N.
11. A coin is placed on a rotating disc spinning at 33■ rpm. The coin does not slip if it is within 10
cm from the axis. Find the coefficient of static friction. Answer: µ = 0.122.
Physics)
1. A body of mass 0.2 kg is whirled in a horizontal circle of radius 0.5 m by a string inclined at 30° to
the vertical. Find: (i) tension in the string (ii) speed of the mass. Answer: T = 2.3 N, v = 1.7 m/s.
2. A bob of mass 200 g is whirled in a horizontal circle of radius 50 cm by a string inclined at 30° to
the vertical. Find the tension in the string and the speed of the bob. Answer: T = 2.3 N, v = 1.7 m/s.
3. An object of mass 0.5 kg is rotated in a horizontal circle by a string of length 1 m. The maximum
tension before the string breaks is 50 N. Find the greatest number of revolutions per second.
Answer: 1.6 rev/s.
4. A stone of mass 0.8 kg is attached to a string 0.9 m long. The string breaks if tension exceeds
600 N. Find the maximum speed without breaking the string. Answer: 0.85 rev/s.
5. An object of mass 4 kg moves in a vertical circle of radius 1 m with constant speed 3 m/s. Find
the maximum tension in the string. Answer: 76 N.
6. A mass of 0.2 kg moves in a vertical circle of radius 1 m with constant speed. The minimum
tension is 3 N. Find the speed and maximum tension. Answer: v = 5 m/s, Tmax = 7 N.
7. At what angle should a road be banked so that a car moving at 50 km/h can turn safely on a
circular road of radius 200 m? Answer: 5.5°.
8. A mass of 1 kg is attached to a string 1 m long and moves in a horizontal circle of radius 60 cm.
Find the tension and period of motion. Answer: T = 12.5 N, Period = 1.77 s.
9. A string breaks when a force of 25 N acts on it. A mass of 500 g attached to a 1 m string is
rotated in a horizontal circle. Find the maximum revolutions per minute without breaking the string.
Answer: 67.5 rpm.
10. An object of mass 8 kg moves in a vertical circle of radius 2 m with constant speed 6 m/s. Find
maximum and minimum tension. Answer: Tmax = 224 N, Tmin = 64 N.
11. A coin is placed on a rotating disc spinning at 33■ rpm. The coin does not slip if it is within 10
cm from the axis. Find the coefficient of static friction. Answer: µ = 0.122.
