Physicshard · Past Paper
A body is moved from rest along a straight line by a machine delivering constant power. The velocity at time t is proportional to:
At^(1/2)
Bt
Ct^2
D1/t
✓ Correct Answer: A — t^(1/2)
P = Fv = (ma)v = m(dv/dt)v. v dv = (P/m) dt. Integrating both sides, v^2 ~ t, so v ~ sqrt(t).
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