If the unit of length is doubled and the unit of mass is halved, while the unit of time remains the same, how does the unit of power change?

4 views 1 helpful Updated Jul 27, 2026
Appears in NEET UG
Solution ✔ Verified
  • ABecomes 1/4th
  • BBecomes 1/2
  • CBecomes 2 times
  • DBecomes 4 times
Explanation

The dimensional formula for Power is [M L² T^-3]. Let the new unit of mass be M' = M/2. Let the new unit of length be L' = 2L. Let the new unit of time be T' = T. New unit of power P' = [M' (L')² (T')^-3] = [(M/2) * (2L)² * T^-3] = (1/2) * 4 * [M L² T^-3] = 2 * [M L² T^-3]. So, the new unit of power becomes 2 times the original unit. This seems off. Let me recheck. If a unit of power is P_old = M L² T^-3. New unit of power P_new = (M/2) (2L)² T^-3 = (1/2) M * 4 L² T^-3 = 2 M L² T^-3 = 2 P_old. This means the new unit is 2 times the old unit. So a quantity measured in the new units will have a value that is 1/2 of its value in old units. The question asks "how does the unit of power change?". If unit is 2 times larger, a given value will be smaller. If a unit becomes N times, the measured value becomes 1/N times. The options are about the unit itself, not the numerical value. So if the unit becomes 2 times, then the value becomes 1/2. Let's see the options. "Becomes 1/4th, 1/2, 2 times, 4 times". So, the unit of power becomes 2 times. The correct option from calculation is 2 times. Let me double check common interpretation. "How does the unit of power change?" If 1 unit_old = x. And 1 unit_new = y. y = N * x. If N=2, it becomes 2 times. Then a value measured = V_old * x = V_new * y. V_new = V_old * x/y = V_old / N.

Was this solution helpful?
1
Practice MCQs on Units & Dimensions — test yourself with instant answers. Start Practising