A body is moving unidirectionally under the influence of a source of constant power. Its displacement in time t is proportional to
(i) t1/2 (ii) t (iii) t3/2 (iv) t2
The correct answer is (iii).
Explanation:
Power, P = F v = k (constant)
Considering the dimensions,
[P] = [F][v]
⇒ [P] = [MLT-2][LT-1]
⇒ [P] = [ML2T-3]
So, [ML2T-3] = k
⇒ [L2T-3] = k
⇒ [L2/T3] = k
⇒ [L2] = k[T3]
⇒ [L2] ∝ [T3]
⇒ [L] ∝ [T3/2]
Hence, l ∝ t3/2