Question

Question:
Two trucks of equal length 5m having speeds 22kmph and 14kmph, moving toward each other in parallel lanes.
When will they cross each other?​

Answer 1

Answer:-

Given:-

length of each truck = 5 m

Speed of first truck = 22 km/h

Speed of second truck = 14 km/h.

It is also given that, they are moving towards each other. That is, they're travelling in opposite direction.

We know that,

Relative speed of two objects moving in opposite direction will be the sum of their speeds.

So, Relative speed of the two trucks = 22 + 14 = 36 km/h.

We know;

Time = Distance/Speed

So,

⟹ Time taken by them to cross each other = [ sum of lengths of two trucks / Relative speed ]

⟹ Time taken = (5 + 5) / (36 × 5/18)

[ ∵ 1 km/hr = 5/18 m/s ]

⟹ Time taken = 10/10

⟹ Time taken = 1 sec

∴ Time taken by both the trucks to cross each other is 1 second.

Answer 2

Given :-

Two trucks of equal length 5m having speeds 22kmph and 14kmph, moving toward each other in parallel lanes.

To Find :-

time when they will cross each other

Solution :-

At first total speed

$\sf Speed = t_1 + t_2$

Speed = 14 + 22

Speed = 36 kmph

Now

Speed in m/s

$\sf 36 \times \dfrac{5}{18}$

10 m/s

Now,

Total length = 5 + 5 = 10 m

Now

Time = Distance/Speed

Time = 10/10

Time = 1/1

Time = 1 sec