
Velocity
Two trains each 440 feet long, run towards each other on parallel lines at the same uniform velocity. They meet and pass each other in seven and half seconds.
What is the velocity of each train in miles per hour?
Trains have to pass each other length. But two trains with same speed, pass each other at the same time. So how could I calculate this?

$\displaystyle \text{velocity} = \text{distance} \div \text{time}$
Since the 2 trains are heading towards eachother, the velocity solved will be double of a single train.
2 trains are 880 feet long.
$\displaystyle 2 \times \text{velocity} = 880 \text{ft} \div 7.5 \text{seconds}$
In short, the 2 trains combined velocities cancel out the extra distance of both trains.
$\displaystyle \text{velocity} = 440 \text{ft} \div 7.5 \text{seconds}$