Question

A 280g toy does 12 push-ups in a minute displacing it's center of mass by a distance of 5.5 cm for each pushup . determine the total work done by the toy while moving downward.​

Answer 1

Given:

A 280g toy does 12 push-ups in a minute displacing it's center of mass by a distance of 5.5 cm for each pushup.

To find:

Total work done by the toy while moving downwards.

Calculation:

During push-upwards , the toy performs work against gravitational field , let the work done be w ;

$\therefore \: \sf{w = n \times (mgh)}$

$= > \: \sf{w = 12 \times (\dfrac{280}{1000} \times 10 \times \dfrac{5.5}{100} ) }$

$= > \: \sf{w = 12 \times (\dfrac{28}{10} \times \dfrac{5.5}{100} ) }$

$= > \: \sf{w = 12 \times (\dfrac{28 \times 5.5}{1000} ) }$

$= > \: \sf{w = 1.848 \: joules}$

Now , this work done gets stored in the form of gravitational potential energy in the object , so the work done while going downwards will be negative of the work done while going upwards.

$= > \: \sf{w_{(downwards)} = - 1.848 \: joules}$

So, final answer is:

$\boxed{ \rm{w_{(downwards)} = - 1.848 \: joules}}$