The car moved at a speed of 90 km / h for 20 minutes and then at a speed of 72 km / h for 10 minutes. Find the average speed of the car in the 30 minutes Can you bring the formula, to be more specific,

The car moved at a speed of 90 km / h for 20 minutes and then at a speed of 72 km / h for 10 minutes. Find the average speed of the car in the 30 minutes Can you bring the formula, to be more specific,

It can be seen that the driving distance in the previous stage is 90 * 20 / 60 = 30 km. The driving distance in the later stage is 72 * 10 / 60 = 12 km. Then the average speed of the car in the 30 minutes is 42 / (30 / 60) = 84 km / h. If calculated from the formula, it is: S1 = V1 * T1 = 90 * 20 / 60 km = 30 km, S2 =

When a car runs at a constant speed of 72 km / h for 10 minutes, the consumption of gasoline is 1.2 kg. When the car runs at a constant speed, the traction force is f = 12000n, and the calorific value of gasoline is q = 4.6 × 10 seventh power coke / kg?

1.2 × 4.6 × 10 ^ 7 = 5.52 × 10 ^ 7

The speed of a car is 5 / 6 km / min. how many km can it travel in 10 minutes? 1 / 2 hour?

50/6,5/12

A batch of goods and materials need to be transported from place a to place B within one hour. When someone drives a car, he has walked 40 km in the first half hour. What is the speed in the second half hour

100-40=60(km)
60÷0.5=120(km\h)