The shadow height and its rate of change vary depending on the person s position.
Person walking from wall height light rate of change.
A 2 meter tall person is initially 10 meters from the wall and is moving towards the wall at a rate of 0 5 m sec.
The rate of change of the change in position of his shadow s head dl dt is then positive as well reflecting the fact that l increases as.
James che brian alford and mani ramachandran torrey pines high school march 2011.
If the person walks away from the the light as in our example his position x value is increasing and so dx dt is 1 5 m s a positive value.
The only thing that changes is the sign of the rates.
Example 7 a spot light is on the ground 20 ft away from a wall and a 6 ft tall person is walking towards the wall at a rate of 2 5 ft sec.
A spotlight is located on the ground 40 ft from the wall.
Is the shadow increasing or decreasing in height at this time.
13 using the previous problem what is the rate at which the shadow changes when the person is 10 ft from the wall if the person is walking away from the wall at a rate of 2 ft sec.
A light is mounted on a wall 5 meters above the ground.
The slider moves the person between the spotlight and the wall.
You might call it the shadow problem or you might know it as the lamp post problem or maybe just the light problem guy or girl of a certain height walks.
A spotlight is located on the ground 40 ft from the wall.
How fast does the height of the person s shadow on the wall change when the person is 10 ft from the wall.
How fast is the height of the shadow changing when the person is 8 feet from the wall.
The classic related rates problem.