Question

A 1000-kg car has 50,000 joules of kinetic energy. What is the speed?

Answer 1

K.E = 1/2mv^2

The kinetic energy is 50,000 J and the mass of the car is 10,000 kg. 

50,000 J = 1/2(10,000kg)v^2
Solve for v (velocity) 
50,000 J = 5,000 kg x v^2
10 = v^2
$\sqrt{10} = v$
about 3 m/s (in terms of significant figures) 

Answer 2

Answer:

½mv²= KE  

½(1000)?²= 50000

500*?²= 50000

500          500

? ²=100

Square root  

?= 10

10 m/s is you answer