A 2.5-kg object falls vertically downward in a viscous medium at a constant speed of 2.5 m/s. How much work is done by the force the viscous medium exerts on the object as it falls 80 cm?

The workdone is

Explanation:

From the question we are told that

    The mass of the object is

     The speed of fall is

     The depth of fall is  

Generally according to the work energy theorem

Now here given the that the velocity is  constant  i.e   then

We have that

So in terms of workdone by the potential energy of the object and that of the viscous liquid we have

Where   is workdone by viscous liquid

              is the workdone by the object which is mathematically represented as

So  

=>    

substituting values

the duration of a photographic flash is related to an rc time constant, which is 0.100 μs for a certain camera.