Problems on Calculating Speed
Here we will learn to solve different types of problems on calculating speed.
We know, the speed of a moving body is the distance traveled by it in unit time.
Formula to find out speed = distance/time
Word problems on calculating speed:
1. A man walks 20 km in 4 hours. Find his speed.
Solution:
Distance covered = 20 km
Time taken = 4 hours
We know, speed = distance/time
= 20/4 km/hr
Therefore, speed = 5 km/hr
2. A car covers a distance of 450 m in 1 minute whereas a train covers 69 km in 45 minutes. Find the ratio of their speeds.
Solution:
Speed of car = Distance covered/Time taken = 450/60 m/sec = 15/2
= 15/2 × 18/5 km/hr
= 27 km/hr
Distance covered by train = 69 km
Time taken = 45 min = 45/60 hr = 3/4 hr
Therefore, speed of trains = 69/(3/4) km/hr
= 69/1 × 4/3 km/hr
= 92 km/hr
Therefore, ratio of their speed i.e., speed of car/speed of train = 27/92 = 27 : 92
3. Kate travels a distance of 9 km from her house to the school by auto-rickshaw at 18 km/hr and returns on rickshaw at 15 km/hr. Find the average speed for the whole journey.
Solution:
Time taken by Kate to reach school = distance/speed = 9/18 hr = 1/2 hr
Time taken by Kate to reach house to school = 9/15 = 3/5 hr
Total time of journey = (1/2 + 3/5) hr
Total time of journey = (5 + 6)/10 = 11/10 hr
Total distance covered = (9 + 9) km = 18 km
Therefore, average speed for the whole journey = distance/speed = 18/(11/10) km/hr
= 18/1 × 10/11 = (18 × 10)/(1 × 11) km/hr
= 180/11 km/hr
= 16.3 km/hr (approximately)
Relationship between Speed, Distance and Time
Problems on Calculating Distance
Two Objects Move in Same Direction
Two Objects Move in Opposite Direction
Train Passes a Moving Object in the Same Direction
Train Passes a Moving Object in the Opposite Direction
Two Trains Passes in the Same Direction
Two Trains Passes in the Opposite Direction
8th Grade Math Practice
From Problems on Calculating Speed to HOME PAGE
Didn't find what you were looking for? Or want to know more information about Math Only Math. Use this Google Search to find what you need.
|
|
New! Comments
Have your say about what you just read! Leave me a comment in the box below. Ask a Question or Answer a Question.