# In a car with 1 kW of power, the engine consumes 330 g of gasoline per 1 hour. Determine the efficiency of the engine.

N = 1 kW = 1000 W.

m = 330 g = 0.33 kg.

t = 1 h = 3600 s.

q = 4.6 * 10 ^ 7 J / kg.

Efficiency -?

The efficiency coefficient of the vehicle is expressed by the formula: efficiency = Ap * 100% / Az, where Ap is useful work, Az is work expended.

The useful work Ap will be expressed by the formula: Ap = N * t, where N is the engine power, t is the engine operating time.

Ap = 1000 W * 3600 s = 3600000 J.

The expended work Az is the work that is performed due to the thermal energy that is released in the engine: Az = Q.

Q = q * m, where q is the specific heat of combustion of gasoline, m is the mass of gasoline that has burned.

Q = 4.6 * 10 ^ 7 J / kg * 0.33 kg = 15180000 J.

Efficiency = 3600000 J * 100% / 15180000 J = 23.7%.

Answer: the car has an efficiency of 23.7%.