For example, a car was traveling at 60 miles per hour (mph) and hit another car, but there was hardly a dent. The reason is that the second car was traveling in the same direction at 59 mph, so the car was travelling only 1 mph with respect to the second car when the collision Speed<span> is how fast an object is going with respect to an object. </span>Velocity<span> is a measure of the speed in a given direction. You can say the top speed of an airplane is 300 kilometers per hour (kph). But its velocity is 300 kph in a northeast direction. We distinguish between speed and velocity because if you add the speeds of multiple objects, their directions are important. For example, the velocity of an airplane with respect to the ground would vary according to the direction of the wind.</span>
In the given equation, p is the distance from the vertex (0, 0) to the focus of the parabola. Any vertical "light beam" will bounce off the curve and pass through the focus at (0, p).
