Question

Поезд ехал три часа со скоростью v1 км.ч затем сделал трёхчасовую остановку и ехал ещё 4 часа со скоростью v2км.ч составте выражение для средний скоррости поезда найдите средднюю скорость при v1=40 v1=60km/ch

Answer 1

Весь путь равен 40*3+60*4=120+240=360 км
время в пути 3+3+4=10 ч
средняя скорость равна 360/10=36 км/ч

Answer 2

Calculating Average Speed of the Train

To calculate the average speed of the train, we can use the formula:

Average Speed = Total Distance / Total Time

The total time is the sum of the time taken at the first speed and the time taken at the second speed. The total distance is the distance covered at the first speed plus the distance covered at the second speed.

Let's denote: - \( t_1 \) as the time taken at the first speed - \( t_2 \) as the time taken at the second speed - \( v_1 \) as the first speed in km/h - \( v_2 \) as the second speed in km/h

The total time \( T \) is given by: \[ T = t_1 + t_2 \]

The total distance \( D \) is given by: \[ D = v_1 \times t_1 + v_2 \times t_2 \]

The average speed \( V_{avg} \) is given by: \[ V_{avg} = \frac{D}{T} \]

Calculating Average Speed for \( v_1 = 40 \) km/h and \( v_2 = 60 \) km/h

Let's calculate the average speed for \( v_1 = 40 \) km/h and \( v_2 = 60 \) km/h.

Given: - \( v_1 = 40 \) km/h - \( v_2 = 60 \) km/h - \( t_1 = 3 \) hours - \( t_2 = 4 \) hours

Using the above formulas: \[ T = 3 + 4 = 7 \text{ hours} \] \[ D = 40 \times 3 + 60 \times 4 = 120 + 240 = 360 \text{ km} \] \[ V_{avg} = \frac{360}{7} \approx 51.43 \text{ km/h} \]

So, for \( v_1 = 40 \) km/h and \( v_2 = 60 \) km/h, the average speed of the train is approximately 51.43 km/h.