July 20th, 2017, 04:50 AM  #1 
Member Joined: Dec 2011 Posts: 61 Thanks: 0 
Hi guys. How to solve this? I left physics and maths a long time ago. SpiderMan needs to get to Mary Jane. Find x and let us know how long the web should be. Kindly appreciated with your great minds. Thank you. This is the diagram. Last edited by skipjack; July 20th, 2017 at 06:12 AM. 
July 20th, 2017, 06:08 AM  #2 
Global Moderator Joined: Dec 2006 Posts: 18,544 Thanks: 1476 
What is the web (or line or whatever it's called) attached to at the top end? Also, can the line stretch? 
July 20th, 2017, 06:15 AM  #3 
Member Joined: Dec 2011 Posts: 61 Thanks: 0  
July 20th, 2017, 06:30 AM  #4 
Global Moderator Joined: Dec 2006 Posts: 18,544 Thanks: 1476 
How can he swing across using it if the far end isn't attached to something? It can't be attached to the building where Mary Jane is as she's on the top of that building.

July 20th, 2017, 06:33 AM  #5 
Member Joined: Dec 2011 Posts: 61 Thanks: 0  
July 20th, 2017, 06:59 AM  #6 
Math Team Joined: Jul 2011 From: Texas Posts: 2,698 Thanks: 1356 
looks like he starts h = 10 meters above the lowest point of his swing, so the initial potential energy will be converted to kinetic energy ... $mgh = \dfrac{1}{2}mv^2 \implies v^2 = 2gh$ net force at the bottom of the swing is centripetal ... $\dfrac{mv^2}{r} = T  mg$ substitute the given and known values and solve for $r$ which appears to be the value $x$. 