Work is said to be one Joule when a force of
- (a)4 N moves an object by 25 cm.
- (b)2 N moves an object by 1 m.
- (c)1 N moves an object by 1 cm.
- (d)1 N moves an object by 50 cm.
Correct — A, 4 N moving an object by 25 cm. Work equals force times the distance moved in the direction of the force, W = F × d. With 4 N over 25 cm, that is 4 N × 0.25 m = 1 J, which matches the definition of one joule as the work done when a force of one newton moves a body one metre. The other options give 2 J, 0.01 J and 0.5 J, none of which equals one joule.
- (b)2 N moves an object by 1 m. — 2 N × 1 m = 2 J, which is twice the required one joule.
- (c)1 N moves an object by 1 cm. — 1 N × 0.01 m = 0.01 J, only a hundredth of a joule.
- (d)1 N moves an object by 50 cm. — 1 N × 0.5 m = 0.5 J, half a joule, not one joule.
In physics, work is done when a force moves its point of application through a distance, and it is measured as force multiplied by the displacement in the direction of the force, W = F × d. Its SI unit is the joule, defined as one newton-metre.
Convert every distance to metres before multiplying, because the centimetre options are the trap. One joule is one newton-metre, so any force-distance pair whose product is one in SI units is the correct choice.
- Work done equals force times displacement in the direction of the force, W = F × d.
- One joule is the work done when a force of one newton moves a body through one metre.
- 4 N × 0.25 m equals 1 J, matching the definition.
- The joule is the SI unit of both work and energy.
- Forgetting to convert centimetres to metres before multiplying.
- Assuming a force does one joule regardless of the distance moved.
Asked as a numerical definition of the joule; find the force-and-distance pair whose product is 1 J in SI units.
No directly related past PYQ was found.
- practice — not a real PYQ
One joule of work is done when a force of 1 N moves a body through
- (a)1 cm
- (b)10 cm
- (c)1 m
- (d)100 m
Answer(c) 1 m — one joule equals one newton-metre.
- practice — not a real PYQ
A force of 10 N moves a body 2 m in its own direction. The work done is
- (a)5 J
- (b)12 J
- (c)20 J
- (d)0.2 J
Answer(c) 20 J — W = 10 N × 2 m.