Section 2 - Q2
Question:
Two trucks of equal length 10m having speeds 11kmph and 25kmph moving toward each other in parallel lanes.
When will they cross each other?
Answers
Given :
• Length of the two trucks is equal.
• Length of both the trucks = 10 m
• The speed of the first truck = 11 km/h
• The speed of the second truck = 25 km/h
To find :
• Time taken to cross each other
Solution :
Relative speed of both the trucks = Sum of their speeds
→ Relative speed = Speed of first truck + Speed of second truck
→ Relative speed = 11 + 25
→ Relative speed = 36
Therefore, the relative speed of the trucks = 36 km/h
Time taken to cross each other = Length of both the trucks ÷ Relative speed
Firstly, convert the relative speed of the trucks into m/s. Because units should be same for right answer.
Mulitply the value by 5/18 to convert it from km/h into m/s.
→ Relative speed = 36 × 5/18
→ Relative speed = 2 × 5
→ Relative speed = 10
Therefore, relative speed = 10 m/s
Now, Substitute the value in the formula :-
→ Time taken = Sum of length of both the trucks ÷ Relative speed
→ Time taken = (10 + 10)/10
→ Time taken = 20/10
→ Time taken = 2
Therefore, the time taken by the trucks to cross each other = 2 seconds