Revise Mechanics! (2)
A simple pendulum is suspended from a peg on a vertical wall. The pendulum is pulled away from the wall to a horizontal position(see figure) and released. The ball hits the wall, the coefficient of restitution being .
What is the minimum number of collisions after which the amplitude of oscillations becomes less than 60 degrees?
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 ball starts at 90 degrees. Each time it hits, it looses 5 2 of whatever angle it just was. So we can set up the equation A = 9 0 ( 5 2 ) t . We want to see when A is 60, so set A to 60 and solve for t. The answer you get should be a decimal. Round up, for we are looking for a whole swing. The answer is 4.