The kinetic energy of a car at a speed of 72 km / h is 300 kJ. Determine the weight of the vehicle.

For a closed system, the kinetic energy of the car is equal to:
Ek = (mV ^ 2) / 2, where Ek is the kinetic energy of a moving vehicle (Ek = 300 kJ = 300 * 10 ^ 3 J), m is the mass of the vehicle (1.5 kg), V is the vehicle speed (V = 72 km / h = 72 * 1000/3600 m / s = 20 m / s).
Let’s express and calculate the mass of the car:
m = 2Ek / V ^ 2 = (2 * 300 * 10 ^ 3) / (20 ^ 2) = 600000/400 = 1500 kg = 1.5 tons.
Answer: The mass of the car is 1.5 tons.