Question

Из двух городов , расстояние между которыми равно 480 км , навстречу друг другу одновременно выехали два автомобиля . найдите скорость второго автомобиля ,если скорость первого равна 50км./ч. и автомобили встретились через четыре часа после выезда

Answer 1

480:4=120км/час скорость сближения(сумма скоростей)
120-50=70км/час скорость второго

Answer 2

Problem Analysis

We are given that two cars start simultaneously from two different cities and meet each other after four hours. The distance between the cities is 480 km, and the speed of the first car is 50 km/h. We need to find the speed of the second car.

Solution

Let's assume the speed of the second car is x km/h.

The distance covered by the first car in 4 hours is: Distance1 = Speed1 * Time = 50 km/h * 4 hours = 200 km.

The distance covered by the second car in 4 hours is: Distance2 = Speed2 * Time = x km/h * 4 hours = 4x km.

Since the two cars meet each other, the sum of the distances covered by both cars should be equal to the total distance between the cities: Distance1 + Distance2 = 480 km.

Substituting the values of Distance1 and Distance2, we get: 200 km + 4x km = 480 km.

Simplifying the equation: 4x km = 480 km - 200 km, 4x km = 280 km.

Dividing both sides of the equation by 4, we get: x km = 280 km / 4, x km = 70 km/h.

Therefore, the speed of the second car is 70 km/h.

Answer

The speed of the second car is 70 km/h.

Verification

Let's verify the answer using the given information.

The distance covered by the first car in 4 hours is: Distance1 = Speed1 * Time = 50 km/h * 4 hours = 200 km.

The distance covered by the second car in 4 hours is: Distance2 = Speed2 * Time = 70 km/h * 4 hours = 280 km.

The sum of the distances covered by both cars is: Distance1 + Distance2 = 200 km + 280 km = 480 km.

The total distance between the cities is indeed 480 km, which confirms that the answer is correct.

Conclusion

The speed of the second car is 70 km/h.