Question

7. A train which is 100 meters long is traveling at a speed of 90 km per hour. How many

seconds will it take for this train to pass completely through a 300 meter tunnel?
A 4
B 8
C 12
D 16
E 20

The answer is D, 16. How do you get 16 tho?

Answer 1

D; 16 seconds

Explanation:

speed = distance/time

speed = 90 km/hr

We need to convert this to m/s because the tunnel is in meters and the time is in seconds:

`(90km)/(hr) * (1hr)/(3600s) *(1000m)/(1km) =25m/s`

distance = 300 m (tunnel) + 100 m (train) = 400 meters

Solving for time:

`25m/s=(400m)/(t) \\(25m/s)(t)=400m\\t=(400m)/(25m/s) \\t=16 s`