When a stone tied to a string is whirled in a circle, the work done on it by the string :
- A. is positive.
- B. is negative.
- C. is zero. ✓
- D. depends on the mass of the stone.
Correct Answer: C. is zero.
Explanation
The tension in the string provides the centripetal force, which acts perpendicular to the instantaneous displacement of the stone. Therefore, the work done is W = Fd \cos(90^\circ) = 0.
Related questions on Physics
- The rule to determine the direction of a current induced in a coil due to its rotation in a magnetic field is :
- A car travels a total distance L. It travels half the distance with speed v_1 and the other half with speed v_2. The average speed of th...
- The linear momentum of a particle is conserved if :
- Assume 'A' does 500 J of work in 'x' minutes and 'B' does 1000 J of work in 20 minutes. If the power delivered by 'A' is P_1 and 'B' is $P...
- A sound wave travelling at a speed of 330 m/s produces 20 crests and 20 troughs in 0.1 second. The wavelength of the sound wave is: