Question

In a fission reaction of U-235, there was a release of 9.20 × 1011 kJ of energy. What amount of mass in kilograms would have been lost?

Recall that c = 3 × 108 m/s.

Answer 1

Answer : The amount of mass in kilograms lost would be,
`1.022* 10^(-2)Kg`

Solution : Given,

Energy of released in the reaction =
`9.20* 10^(11)KJ`

Speed of light = c =
`3* 10^8m/s`

Formula used :

`E=m* c^2`

where,

E = energy released

m = mass

c = speed of light

Now put all the given values in the above formula, we get the amount of mass would have been lost.

`9.20* 10^(11)KJ=m* (3* 10^8m/s)^2`

`m=1.022* 10^(-5)KJ/m^2s^(-2)=1.022* 10^(-5)* 10^3Kg=1.022* 10^(-2)Kg`

conversion :
`(1KJ/Kg=10^3m^2/s^2)`

Therefore, the amount of mass in kilograms lost would be,
`1.022* 10^(-2)Kg`

Answer 2

e = mc^2

m = e / c^2

Plug in your numbers in the appropriate units.
m=1.02 × 10^-5