Question

Автомобиль проехал расстояние 2 км со скоростью 20 м-с , а потом 4,5 км со скоростью 15 м-с . Какова средняя скорость движения автомобиля на всём пути?

Answer 1

t=  , тоесть время для первого 2000м / 20м/с= 100с

для второго тела 4500м / 15м/с= 300с

средняя скорость равна vср=  =  = 1, 6 м/с 

Answer 2

Дано:

S1=2km=2000M

V1=20M/c

S2=4,5km=4500M

V2=15 M/c

Vcp-?

Vcp=S/t

S=S1+S2

t=t1+t2

S=2000+4500м=6500м

t1=S1/V1, t 1=2000M/20M/c=

=100c

t 2=S2/V2, t 2=4500M/15 M/c=

=300c

t=100c+300c=400c

Vcp=6500м/400c=16,25 M/c

 

Answer 3

Calculation of Average Speed

To calculate the average speed of the car over the entire distance, we need to find the total time taken and the total distance traveled.

The car first traveled a distance of 2 km with a speed of 20 m/s. To find the time taken for this part of the journey, we can use the formula time = distance / speed. Therefore, the time taken for the first part is:

time1 = 2 km / 20 m/s = 0.1 hours.

Next, the car traveled a distance of 4.5 km with a speed of 15 m/s. Using the same formula, we can find the time taken for this part:

time2 = 4.5 km / 15 m/s = 0.3 hours.

To find the total time taken for the entire journey, we add the times for each part:

total time = time1 + time2 = 0.1 hours + 0.3 hours = 0.4 hours.

The total distance traveled is the sum of the distances for each part:

total distance = 2 km + 4.5 km = 6.5 km.

Now, we can calculate the average speed using the formula average speed = total distance / total time:

average speed = 6.5 km / 0.4 hours = 16.25 km/h.

Therefore, the average speed of the car over the entire journey is 16.25 km/h.