Problems Based on Speed


 
 
Concept Explanation
 

Solving Statements Involving Speed

Solving Statements Involving Speed: In these types of problems we consider the relative speed of the two objects. When the two objects are moving in the same direction, the relative speed is the difference of the speed of the two objects. When the two objects are moving in the opposite direction , the relative speed is found as the sum of speed of the two objects.

For Example: The distance between two points A and B is 340 Km. Two trains start together one from station A and other from station B , The speed of one train is 5 km/hr more than the other train. If the distance between the two trains after two hours is 30 km. Find the speed of the two trains.

Let the speed of one train =  x km/hr

Speed of other train will be = x +5 km/hr

large Speed = frac{distance}{time}

Distance = Speed X time

Distance travelled by first train in two hours = 2x

Distance travelled by the second train in two hours = (x+5) X 2= 2x+10

Distance between the two trains after two hours = 30km

According to the question

 Distance travelled by one train + distance travelled by second train + 30 = 340

2x+ 2x+ 10  + 30 = 340

4x+ 40 = 340

4x= 300

x= 75 km/hr

Speed of one train = 75 kmhr

Speed of second train = 75 + 5 = 80 kmhr

Sample Questions
(More Questions for each concept available in Login)
Question : 1

In a flight of 2800 km, an aircraft was slowed down due to bad weather. Its average speed for the trip was reduced by 100 km/hr and the time increased by 30 minutes. Find the original duration of the flight.

Right Option : C
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Explanation
Question : 2

On a journey of 100km, Meeta travels at a certain speed for the first 60km, and then increases his speed by 15km/h for the remainder. If the whole journey takes 2 hours, find his two speeds.

Right Option : D
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Explanation
Question : 3

An express train covers 240 km at a certain speed. Another train, whose speed is 12 km/hr less, takes an hour longer to cover the same distance. Find the speed of the express train in km/hr.

Right Option : B
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Explanation
 
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