A person carries a 15.0 kg box up a flight of stairs. If the topof the stairs is 5.0 m higher than the bottom of the stairs thenhow much work is done by a person on...

(I) A 65.0 -kg firefighter climbs a flight of stairs 20.0 $\mathrm{m}$ high. How much work is required?

Be so got 75 kilogram guy. 75 point. No kilogram equals mass. All right, there clamming up some stairs and they climb up the stairs and they gain 2.5 meters, 2.5 years in height. I want to find out the work that had been done to accomplish Just climb up the stairs. So how do we figure that out? Won't remember. Work is a little time flying is equal to force. Started with distance. Since it's a conservative field, don't worry about the don't, uh, worry about the dimensions here. And what I mean by that is you can just pretend this is one d going up 2.5 meters and that these vectors here between the Force and the displacements are both parallel where, as such, it's just equal to the work is just equal to the multiplication of the magnitude of both of these veterans. You all right that legal to work? No problem is I got the distance sitting right here 2.5 years. Plug it in right away. I don't have the force, though. What is the force in this case? So the force that this guy has to overcome is the force of gravity that's equal to the mass times gravitational celebration. We have the massive 75.8 kilograms. We can actually put this in our absolute value here. All right, so work equals mass times revenue. Well, why by this is which is equal to massive 75 went over 5 75 Oh, kilograms, 9.81 years per second, 2.5 meters on the tail. And there he's got that space is not happening. And what about a distance here? 2.50 meters. That set height that they went up. So you could definitely like this as and the each that would have behind there to find his each earlier crunch shot. This math, the 75.0 multiplied by 9.81 multiplied by 2.50 We're looking at 1000 837 0.5 Tools

And this problem. We have a 75 kilogram person climbing the stairs of vertical light 2.5 meters. And we want to find the work that this person does and climbing these stairs so we can think about this two different ways. The first way would be to recall that our work done. It's gonna be our applied force with blood by our displacement and then multiply it by the coastline of the angle between these two. That angle between our applied force in our displacement here are applied force is gonna be equivalent to that normal force. And the normal force is bouncing out our gravitational force. So are applied is just gonna be mg. Our displacement is gonna be our height h and then both the displacement and force our verticals of that angle between 20 So we have assign zero, which is one. So you get MGH and here we can see the second way to think about this. His MGH is also the change in our potential energy, which makes sense. The work that we and do is going to be equal to the difference in energy of our final configuration of being on the top of the stairs as opposed to our initial configuration of being on the bottom. And here we don't have to think about kinetic energy at all because we're starting and finishing with no velocity. So here, that's gonna be equal to 75 kilograms. Gravity 9.1. And then our height is 2.5 meters and up to three significant figures. This gives us 18. 40 Jules.

In problem 3. 75 kg. Firefighter claims of flight of stairs Continental high. How much work is required? So this question is from chapter seven, work and energy. So we have given mass of firefighters. So the mass of fire fighter that is 75 kg. Then we have given the the height of stairs. Uh, the hide of stairs, That is 20 m. Hi. No, we have to calculate the work in discussion. So now, as, uh, the relationship between the work force and displacement that is, uh, w is equal to f d cause. So now the angle between the fourth and displacement is zero. So we can write f d cause zero f D costs zero degree. Now, the angle between the fourth and displacement is zero because the firefighter moving up 20 up 20 m high. So w is equal to f d cor zero and CO zero is one. Now, in case of uh uh, this weekend, also write it as M. G. Ahh. And we can just put the value of, uh, moss isolation due to gravity and height. So the value of a mask that is 75 kg isolation due to gravity, that is 9.8 metre per second. Scare and height is continue with her. And this is the because zero and 40 is simply one. So on solving, we get this. 147 double zero. Jude, this is the work or work we can write. Test 1.47 to 10 days to power four jewel because, uh, this kg meter scared Second, minus two. We can write one goal. This is equal to one, George. So this is our final answer. Work is equal to 147 double zero or 1.47 to 10 days to power four jewels.

7.3. We have a 75 kilogram firefighter climbing flight of steps that's 20 meters high, since we want to know how much work is required for this so but work. Since the force is going to be constant, it's going to be just his weight is the minimum amount of force required. The co sign Seda. Now the firefighter is moving by 20 meters. So the angle between the force of this placement at zero degrees so close and they did become one. Now, of course, the steps. You know, I like this, but we're just told what the change in height is. So whatever this distance is, doesn't matter. If we were told that he, you know, goes a distance of 20 meters of fighter steps, that's it, like, you know, 15 degrees or something. Then we have to put that in here. But that's not what we're doing. We just know the change in high and because gravity is a conservative for us, it doesn't matter what distance you go perpendicular to the direction of the force. And so the work required for this and the forces is wait again. So inviting GI. And so this is 1.47 times 10 to the fourth Jules