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- Homework Statement
- A pump is required to lift 790 kg of water (about 210 gallons) per minute from a well 14.1 m deep and eject it with a speed of 17.5 m/s. (a) How much work is done per minute in lifting the water? (b) How much work is done in giving the water the kinetic energy it has when ejected? (c) What must be the power output of the pump?

- Relevant Equations
- Kinetic Energy, Work, Power

Hello,

I’ll start by saying I have the answers and the steps to the solutions, but there’s a comprehension disconnect somewhere that I’m trying to figure out. There are two parts to my question but the second one may not apply depending on the answer to the first. I wasn’t sure from the forum rules if I could include the actual solutions to the problem I‘m asking about, so I tried to do without, but let me know if it’d be better to add them.

KE: Kinetic Energy

W: Work

F: Force

s: Distance

1) Right now my understanding is that W = F * s and W = KE2 - KE1 are identical for the same scenario, however, (a) and (b) have different answers. I don’t fully understand why. Working theory is that the first two questions are actually looking at different parts in the system, but I would appreciate it if someone could confirm and clarify it a bit more.

2) If it’s that the problem is looking at the system in parts then I understand why the answer to (c) uses the sum of (a) and (b). If this is not the case though then I remain confused.

Thank you for taking a look.

I’ll start by saying I have the answers and the steps to the solutions, but there’s a comprehension disconnect somewhere that I’m trying to figure out. There are two parts to my question but the second one may not apply depending on the answer to the first. I wasn’t sure from the forum rules if I could include the actual solutions to the problem I‘m asking about, so I tried to do without, but let me know if it’d be better to add them.

KE: Kinetic Energy

W: Work

F: Force

s: Distance

1) Right now my understanding is that W = F * s and W = KE2 - KE1 are identical for the same scenario, however, (a) and (b) have different answers. I don’t fully understand why. Working theory is that the first two questions are actually looking at different parts in the system, but I would appreciate it if someone could confirm and clarify it a bit more.

2) If it’s that the problem is looking at the system in parts then I understand why the answer to (c) uses the sum of (a) and (b). If this is not the case though then I remain confused.

Thank you for taking a look.