Question

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?

Answer 1

257.14 W

Explanation:

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

Approximately `685.7` watts.

Explanation:

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"`