Question

How fast must a 1000 kg car be moving to have a kinetic energy of 1.0 kWh

Answer 1

1 watt = 1 Joule per second
1 kW = 1,000 watts = 1,000 J/s
1 hour = 3600 seconds
==> 1 kWh = 3,600,000 Joules

Kinetic energy:  KE = 1/2 m v²

3,600,000 J = (1/2) (1,000 kg) (v²)

v² = (3,600,000 J) / (500 kg)  = 7,200 m²/s²

v = √ (7,200 m²/s²)  =  84.8 m/s   (about 190 mph)   

Answer 2

From definition 1 kWh = 3600000 J

The formula for KE = 1/2 * m * v^2
3600000 = 1/2 * 1000 * v^2
3600000 = 500v^2
v^2 = 7200
v = 84.85 m/s