Question

The energy produced by a 22.1 W bulb is harnessed and used to lift a 88.5 kg weight. If there are no frictional losses and the bulb runs for 1,281 seconds, how high will the weight rise, in m?

Answer 1

We know from the Definition of power,

From this relation we can calculate the work done,

As per the question the workdone by the Electric bulb is harnessed and is used to lift the mass to certain height.

Let us it lift the mass to a height H.

The workdone by the electric bulb is harnessed and used up in lifting the object to the height, ie workdone by bulb is stored in potential enery of the object.

Potential energy stored in the object at height H is given as,

Where M is mass of object.

g is accceleration due to gravity.

H is the height of object.

From Conservation of Energy principle if their are no any energy losses then Work done must be equal to potential energy stored in the object.

Solving for H,

Putting values,

Power = 22.1 Watt

Time = 1281 Seconds

Mass, M = 88.5 kg

Acceleration due to gravity, g = 9.8 m/s^2

Putting values,

On solving we get,

H = 32.64 meter. /* Ans*/

This is the value of the height of mass of 88.5 kg lifted.

/* In case of any difficulty in understanding please comment, I will be happy to help. */

Thank you. :)