Question

Определить КПД двигателя автомобиля, если при скорости 100 км/ч он развивает мощность 52 кВт и при этом затрачивает 10 л бензина на пути 100 км. Теплота сгорания бензина q=4,5 * 107 Дж/кг; плотность: ρ= 700 кг/м3.

Answer 1

N=A/t
A=Nt=52000*3600=187200000[Дж]=187.2[МДж]
t=S/V=100/100=1[ч]=3600[c]
КПД=A/Q
Q=r*m=r*V(объембензина)*ро(плотностьбензина)=4,5*10^7*10*10^(-3)*700=
=31.5*10^7{Дж}
КПД=A/Q=187.2*10^6/315*10^6=187.2/315=0.59*100=59%

Answer 2

Calculating the Efficiency of the Car Engine

To determine the efficiency of the car engine, we can use the formula for efficiency, which is given by:

Efficiency (η) = Output / Input

Where: - Output = Useful work done by the engine - Input = Total energy supplied to the engine

Calculating Output Power

The output power of the engine can be calculated using the formula:

Output Power (P) = Force × Velocity

Given that the car is traveling at a speed of 100 km/h, we can convert this to meters per second (m/s) as follows:

100 km/h = (100 × 1000) / 3600 = 27.78 m/s

Now, using the formula for power, we can calculate the output power:

P = Force × Velocity = F × v

Calculating Input Energy

The input energy can be calculated using the energy content of the fuel and the amount of fuel consumed.

The energy content of the fuel (q) is given as 4.5 × 10^7 J/kg, and the density of the fuel (ρ) is 700 kg/m^3.

The input energy can be calculated using the formula:

Input Energy = Energy content of fuel × Mass of fuel

Given that the car consumes 10 liters of fuel to travel 100 km, we can calculate the mass of the fuel using the density of the fuel:

Mass of fuel = Volume of fuel × Density of fuel = 10 L × 700 kg/m^3

Calculating Efficiency

Now that we have the output power and the input energy, we can calculate the efficiency of the car engine using the formula:

Efficiency (η) = Output / Input

Let's calculate the efficiency using the provided values and formulas.

Output Power (P) = F × v = 52,000 W Input Energy = Volume of fuel × Density of fuel × Energy content of fuel = 10 L × 700 kg/m^3 × 4.5 × 10^7 J/kg Now, we can calculate the efficiency using the formula:

Efficiency (η) = Output / Input

η = P / Input Energy = 52,000 W / (10 L × 700 kg/m^3 × 4.5 × 10^7 J/kg)

By calculating the above expression, we can determine the efficiency of the car engine.