Question

Грузовая машина проезжает расстояние между двумя городами за 30 часов,а легковая - за 20 часов.Машины одновременно выехали из этих городов навстречу друг другу.Через сколько часов они встретятся?

Answer 1

Problem Analysis

We are given that a truck travels a distance between two cities in 30 hours, while a car travels the same distance in 20 hours. Both vehicles start from their respective cities and travel towards each other. We need to determine how many hours it will take for them to meet.

Solution

To solve this problem, we can use the concept of relative speed. The relative speed between the truck and the car is the sum of their individual speeds. Let's assume the distance between the two cities is D.

The speed of the truck is given by D/30 (since it covers the distance in 30 hours), and the speed of the car is given by D/20 (since it covers the distance in 20 hours).

The relative speed of the truck and the car is the sum of their individual speeds: D/30 + D/20.

To find the time it takes for them to meet, we can use the formula:

Time = Distance / Speed

Substituting the values, we have:

Time = D / (D/30 + D/20)

Simplifying the expression, we get:

Time = 600D / (20D + 30D)

Simplifying further, we have:

Time = 600D / 50D

The distance D cancels out, and we are left with:

Time = 12 hours

Therefore, the truck and the car will meet after 12 hours.

Answer

The truck and the car will meet after 12 hours.