Basic physics?

Question

A weight lifter is holding a very large mass of total 200lb. If he listed this weigh through a vertical distance of 2 m calculate the work done, and therefore energy expanded for joules!

Thanks.

Answer 1

200lb= 200* 0.453kg=0.906kg

Work done lifting 2m high: E= mgh

                                             E=0.906kg* 9.81m/s^2 * 2m

                                             E=ca 17.8 Nm=17.8Joule.

I do not understand why you write that this body is a very large mass.

Answer 2

The formula for work done (J) = force(N) x distance (m).

so, we need to convert 200lbs to kg which then can be converted to Newtons.

2.2 lbs =1kg so 200lbs = 91 kg

1kg = 10N so 91kg = 910 N

910N x 2m= 1820J

Answer 3

the answer is zero. there is no work done for this. because he is holding it.

I am sure about that no doubt

Answer 4

Work Done = Force x distance

First convert lb into kg

200 lb =200/2.2 =90.9 kg

Now to find the force we use the weight

w=mg = 90.9 * 9.8 = 890.82N

Work Done = 980.82 x 2

Work Done = 1781.64 J

Rounded sensibly this gives 1782J or 1780J

Hope that helps :-)

Answer 5

Work = change in energy.  The weight's potential energy increases as it is raised 2 m.

Formula is Ep = mgh (mass, gravity, height)

mgh = (90.72 kg) (9.81 m/s^2) (2m) = 1780 J.