A weight lifter lifts an 800 N bar a distance of 3 m is just 3.5 seconds. What is the power output of the lifter in watts?

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Answer 1 · 2018-04-10T14:53:28

257.14 W

First you need to find out the work done by him:
Work = Force x Displacement

Given: Force = $300N$ and Displacement= $3m$
Use this in the formula above:
Work = $300N xx 3m$ = $900Nm$

Now, use the work done you have found to find out the power output:
Power = Work ÷ Time taken
Power = $900Nm ÷ 3.5s$ = $257.14 W$

Answer 2 · 2018-04-10T14:56:54

Approximately $685.7$ watts.

We first find the work done by the weightlifter. Work is expressed through the equation,

$W=F*d$

$F$ is the force in newtons

$d$ is the distance moved in meters

And so, we get, $W=800 \ "N"*3 \ "m"=2400 \ "J"$ .

Power is measured through the equation,

$P=W/t$

$W$ is the work done in joules

$t$ is the time in seconds

Plugging in the values we found, we get,

$P=(2400 \ "J")/(3.5 \ "s")$

$~~685.7 \ "W"$