Question

1. A 1,000-kg car has 50,000 joules of kinetic energy. What is its speed?

Answer 1

Use KE= 1/2mv^2
So... 
50,000=(.5)(1,000)v^2
50,000=500 x v^2
Divide 500 on both sides 
100 = v^2 
Square root both sides to get rid of v^2 
Therefore v = 10 m/s

Answer 2

½mv²= KE  

½(1000)?²= 50000

500*?²= 50000

/500            /500

? ²=100

Square root  

?= 10

10 m/s is you answer