7. A spring balance reads force in Newton. The scale is 20 cm long and reads from 0 to 60 N. Find the potential energy of the spring when it read 40 N.

The potential  energy when it reads 40 N is

Explanation:

From the question we are told that

   The lowest reading of the spring balance is  0 N and this is at  0 cm = 0 m

   The height reading of the spring balance is 60 N  and this is at 20 cm =  0.20 m

   Generally the length corresponding to the reading of 40 N is mathematically represented as

=>    

Generally the potential  energy is mathematically represented as

Here

So  

=>  

answer; i believe that the correct answer is (d) a very small amount of mass

i already answered it by 34/s