Question

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

Answer 1

½mv²= KE

½(1000)?²= 50000

500*?²= 50000

500 500

? ²=100

Square root

?= 10

10 m/s is you answer

Answer 2

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

`√(10) = v`
about 3 m/s (in terms of significant figures)