To move between two floors in a hotel, a man may use either an escalator or a lift. The escalator needs 20 seconds to take the man from one floor to the other. The useful work done against gravity is $W$. The useful power developed is $P$. The lift needs 30 seconds to take the same man between the same two floors. What useful work against gravity does the lift do, and what useful power does the lift develop?
- Auseful work done against gravity by lift: more than $W$; useful power developed by lift: less than $P$
- Buseful work done against gravity by lift: more than $W$; useful power developed by lift: $P$
- Cuseful work done against gravity by lift: $W$; useful power developed by lift: less than $P$
- Duseful work done against gravity by lift: $W$; useful power developed by lift: $P$