A ball is pushed into a spring-loaded launcher with a force of 20 N, which compresses the spring 0.08 m. A) What is the spring constant of the spring
B) Find the elastic potential energy (PEs) stored in the spring (or the work done on the spring)

0.8J

Explanation:

Given parameters:

Force  = 20N

Compression  = 0.08m

Unknown:

Spring constant  = ?

Elastic potential energy  = ?

Solution:

To solve this problem, we use the expression below:

           F = k e

F is the force

k is the spring constant

e is the compression

             20  = k x 0.08

              k  = 250N/m

Elastic potential energy;

       EPE  = k e²    =    x 250 x 0.08²

 Elastic potential energy = 0.8J

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.