Question

Автомобиль массой 1800 кг начинает движение по горизонтальной дороге с постоянным ускорением а-2.5 м/с2. Пренебрегая силами сопротивления, определите мгновенную мошность силы тяги двигателя через промежуток времени 4.0с от начала движения.

Answer 1

P=F*v      F=m*a     v=a*t   (vo=0)

P=m*a²*t=1800*2.5²*4=45*10^3 Вт  (45 кВт)

Answer 2

Calculation of Instantaneous Power

To calculate the instantaneous power of the engine force, we need to use the formula:

Power = Force × Velocity

Given: - Mass of the car (m) = 1800 kg - Acceleration (a) = -2.5 m/s² (negative because it is deceleration) - Time (t) = 4.0 s

To find the force, we can use Newton's second law of motion:

Force = Mass × Acceleration

Plugging in the values, we get:

Force = 1800 kg × -2.5 m/s²

Calculating the force:

Force = -4500 N

Now, we need to find the velocity of the car at the given time. Since the car is starting from rest and has a constant acceleration, we can use the following kinematic equation:

Velocity = Initial Velocity + (Acceleration × Time)

Since the initial velocity is zero, the equation simplifies to:

Velocity = Acceleration × Time

Plugging in the values, we get:

Velocity = -2.5 m/s² × 4.0 s

Calculating the velocity:

Velocity = -10 m/s

Now, we can calculate the instantaneous power using the formula mentioned earlier:

Power = Force × Velocity

Plugging in the values, we get:

Power = -4500 N × -10 m/s

Calculating the power:

Power = 45000 Watts

Therefore, the instantaneous power of the engine force at 4.0 seconds from the start of motion is 45000 Watts.