Question

A 17-car train standing on the siding is started in motion by the train’s engine. 9 cm slack is between each of the cars, which are 9 m long. The engine is tightly connected to the first car and moves at a constant speed of 36 cm/s. How much time is required for the pulse to travel the length of the train? Answer in units of s.

Answer 1

4 seconds

Step-by-step explanation:

There are links between cars, they are in between

1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-16, 16-17.

Here 1 represents the first car which is firmly attached to the engine. So, there are 16 links and each link has a slack of 9 m.

So, total slack

9×16 = 144 cm

Speed of train = 36 cm/s

`\text{Time taken by the pulse}=(Length)/(speed)\\\Rightarrow \text{Time taken by the pulse}=(144)/(36)\\\Rightarrow \text{Time taken by the pulse}=4\ s`

Time taken by the pulse to travel the length of train is 4 seconds.