A classical mechanics problem by Edward Gleason
A ball is dropped from the edge of a cliff 100 meters from the ground. At the same time, a car that is 100 meters from the cliff base starts from rest toward the cliff. How fast will the car have to accelerate toward the cliff so that it arrives at the cliff base at the same moment the ball reaches the ground? (Ignore air resistance and presume the driver isn't afraid of death.) Use 10 meters per second squared as the surface gravity value.
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
1 solution
The car, starting at rest, has to cover 100 meters in the same amount of time the ball has to travel 100 meters to reach the ground. Therefore, in order for the car to travel the same distance as the ball, it has to accelerate at the same rate as the ball, i.e. at g, or 10 meters per second squared. A physics problem that requires reason, not mathematics.