A train 150m long travels at a speed of 72km/h. It crosses a bridge in 13 seconds. Find the length of the bridge.

Question

about direct and inverse variation.

Answer 1

We can solve using this equation:

 

(length of bridge + length of train) = speed of train * time to cross bridge

 

So:

 

x + 150 = 72km/h * 13s

 

Convert 72km/h to m/s => 72000m/3600s => 20m/s (speed of train)

 

Now, solve:

 

x + 150m = 20m/s *13s => x + 150m = 260m => x = 260m - 150m => x = 110m (length of bridge)

Answer 2