Question

a load of bricks is lifted to the second floor of a building. how do work and power relate to this job?
the longer the job takes, the more work is done.
the faster the job is done, the greater the power.
the greater the power applied, the more work is done.
the less work is done, the more power is needed.

Explanation:

1. Recall the definitions: Work ($W$) in lifting is $W = Fd$ (force × distance, here force is weight of bricks, distance is height to second floor, so work depends on these, not time). Power ($P$) is $P=\frac{W}{t}$ (work done over time).
2. Analyze each option:

• First option: Work doesn't depend on time (since $W = Fd$), so longer time doesn't mean more work. Eliminate.
• Second option: From $P=\frac{W}{t}$, for same work ($W$ is fixed as bricks and height don't change), if time ($t$) decreases (job done faster), $P$ increases. Correct.
• Third option: Power is work over time. Greater power could be from less time, not necessarily more work (work is fixed here). Eliminate.
• Fourth option: Less work (but work is fixed) and more power contradicts $P=\frac{W}{t}$ (less $W$ with same $t$ would mean less $P$). Eliminate.

Answer:

B. The faster the job is done, the greater the power.