A 90 kg firefighter needs to climb the stairs of a 20-m-tall building while carrying a 40 kg backpack filled with gear. How much power does he need to reach the top in 55 s?

Question

Accepted Answer

Hey everyone. So this is a very straightforward work and power question. Let's see what they're asking us. We have a construction worker of a massive kg wishing to deliver a 25 kg packet cement to the top of a 25 m building. Using stairs, determine the workers' power that will determine that will enable them to make the delivery in 70 seconds. So the key here is to recall two key equations we have power we can remember is given by work over delta T and work moving in the vertical direction is given by M G H. So we'll rewrite that as power equals M G H over delta T and then take a look at each of these tarps. So from the problem M is given as 72 kg plus 25 kg because the worker is moving his own body plus carrying that cement. Our G is our constant gravitational acceleration 9.8 m per second squared. The height that this work is being done Distance is 25 m given to us in the problem and our Delta T is 70 seconds. So from there you can see it is a very straightforward plug and chug. So we'll have 72 kg plus 25 kg Times 9.8 m/s, squared Times 25 m all over 70 seconds. That comes out to 340 watts. So we look at our potential answer choices and that aligns with answer choice. D that's all we have for this video. We'll see you in the next one.

A 90 kg firefighter needs to climb the stairs of a 20-m-tall building while carrying a 40 kg backpack filled with gear. How much power does he need to reach the top in 55 s?

Verified Solution

Key Concepts

Work and Energy

Power

Mass and Weight