Question

a train travelling at 60 mph enters a tunnel that is 5 miles long. the train is one mile long.how many minutes does it takes for the whole train to pass through the tunnel?

Answer 1

The whole train needs to travel the tunnels length of 5 miles, plus another mile for it to completely pass the tunnel because it is 1 mile long.

Speed of the train = 60mph = 1m/min
Total distance to be covered = 5 + 1 = 6 (5 miles for the tunnel and an extra mile for the train to pass the tunnel) 
Thus time taken = Distance/speed 
= 6/1
= 6 mins

Hope that helps !!

Answer 2

Given:

The speed of the train = 60 mph

The length of the tunnel = 5miles

The length of the train = 1mile

To Find:

The time taken for the whole train to go through the tunnel

Solution:

It takes 6 minutes for the whole train to go through the tunnel.

Since the whole train needs to travel through the tunnel's length, the actual distance that needs to be traveled should be calculated from the end of the train.

Since initially at t=0, the train is at the start of the tunnel

⇒ The end of the train is 1 mile away from the start of the tunnel

⇒The total distance that needs to be traveled by the end of the train = 1 + 5 miles

= 6 miles

Speed of the train = 60mph

Since 60 minutes = 1 hour,

⇒ The speed of the train = 1 mile per minute  

Thus time taken to cover 6 miles = Distance/speed

= 6/1

= 6 minutes