Question:
The US Navy is developing a railgun that uses magnetic field repulsion. The railgun can propel a 981 N projectile at seven times the speed of sound. How much energy is stored in this magnetic field? Assume a complete conversion of energy and a speed of sound of 340 m/s.

Answer choices:
A. 119 MJ
B. 283 MJ
C. 578 MJ
D. 2780 MJ

Respuesta :

The relation of the kinetic energy allows to find the correct result for the energy stored in the electromagnet is:

B) 283 MJ

Kinetic energy is the energy due to the movement of bodies.

          K = ½ m v²

     

Where K is the kinetic energy, m is  the mass and v the spped.

They indicate that the weight of the bodye is W = 981 N and its final velocity is v = 7 [tex]v_s[/tex].

          W = m g

           

Since the projectile starts from rest, its initial velocity is zero, therefore the change in energy is

        ΔK = [tex]K_f - K_o = K_f[/tex]  

we substitute

        ΔK = ½ 981 / 9.8 (7 340) ²

         ΔK = 2.835 10⁸ J

They indicate that all the energy of the electromagnet is transformed into the energy of the projectile,

          Em = K

When reviewing the results, the correct one is:

       B) 283 MJ

In conclusion, using the relationship of kinetic energy we can find the correct result for the energy stored in the electromagnet is:

   B)  283 MJ

learn more about kinetic energy here: brainly.com/question/8101588