How Do You Calculate Power in These Physics Problems?

[SickTechz]

Homework Statement

There are three problems:

1. How much power is required to lift a 10.00 kg barbell at a speed of 3.0 m/s?

2.What is the average power supplied by a 70.0 kg firefighter climbing up a ladder in 10.0 s?

3. A man pulls a wagon with a force directed 22.0˚ above the horizontal. If the horizontal component of the force on the wagon 40.5 N, what is the force exerted on the wagon?

Homework Equations

K = (1/2) * m* V²

P = W/T

The Attempt at a Solution

My physics teacher has been out and we have had a substitute that does not know physics, so I am not entirely sure how to approach these problems. In my eyes, these problems seem to be impossible to solve.[/B]

 

[DrClaude]

You have to provide an attempt at a solution. What have you tried?

 

[SickTechz]

For the First problem, I would start off by plugging in 10.00 into the kinetic energy formula -> (1/2)*10*(3) ^2
then I am not sure how to find the time in order to divide them

For the second problem, I would start off by plugging in 70 for m in the kinetic energy formula. I am not sure what to do after.

For the third problem, I would plug 22 in the work formula and the force of 40.5 N -> w = (40.5)*(cos(22)) I am not sure what to do next

Like I said these problems seem to be unsolvable, but they will be on my midterm, so they must be solvable

 

[CWatters]

For the First problem, I would start off by plugging in 10.00 into the kinetic energy formula -> (1/2)*10*(3) ^2
then I am not sure how to find the time in order to divide them

For the first and second question...

What sort of energy is the bar bell (or fireman) gaining when it's lifted? KE? PE?

 

[haruspex]

For the First problem, I would start off by plugging in 10.00 into the kinetic energy formula

The question does not make it completely clear, but I would assume it means at a constant speed, i.e. don't worry about how it got to that speed - they only want the power required to keep it rising at that speed.
With that understanding, try to answer CWatter's question above.

 

[David Lewis]

For question 1, you will need to calculate how much force is acting on the barbell.