What is the average power output Annette who can lift 250 kg 2.0 m in 2.0 s?

Power is work over time.

Work is force times displacement.

Assuming that Annette lifts at a constant rate, her force must be equal and opposite to gravity's force.

250*9.8 = 2450N

W = Fd

W = (2450) (2.0)

W = 4900 J

4900J/2s = 2450W (watts)

So the answer is 2450W, or 2500W if your teacher uses 10m/s² for gravity.

When Annette lifts 250kg to a height of 2m, she gives it potential energy of

M G H = (250) x (9.81) x (2) = 4,905 joules.

That's the energy that Annette must deliver ... there's nowhere else

it can come from.

If she delivers 4,905 joules of energy in 2 seconds, then she's

supplying that energy at the rate of

4,905 / 2 = 2,452.5 joules per second = 2,452.5 watts.

This is about 3.29 horsepower! I would not want to meet Annette

on a dark street at night, or do anything that would irritate her in

any way.