Guest Posted September 19, 2013 Report Share Posted September 19, 2013 Hey guys, I really have a problem with this math/physics exercise. When dropped, a ball takes 1 second to hit the ground. It then takes 90% of this time to rebound to its new height, and this continues until the ball comes to rest.the total time of motion is: 1+2(0.9)+2(0.9)^2+2(0.9)^3+...A) What is the Sn for the series?B) How long does it take for the ball to come to rest?Help would be very much appreciated. Tnx. Reply Link to post Share on other sites More sharing options...
ctrls Posted September 19, 2013 Report Share Posted September 19, 2013 (edited) What exactly do you need help with?It's a bit confusing because the first term only looks at the time the ball takes to hit the floor, while the other terms look at how the time it takes to bounce back up, then fall back down (hence the 2 seconds). In this case, you have to model as a=2 and r=0.9, then subtract 1 from the total to account for the first term. Everything else should be fairly straightforward, as you just have to plug it all into the respective formulas for the geometric series. Edited September 19, 2013 by ctrls Reply Link to post Share on other sites More sharing options...
-._._.- Posted September 20, 2013 Report Share Posted September 20, 2013 That question looks familiar. But sadly, I don't remember how to do the question. Sorry. Reply Link to post Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.