Learning Resources

Fun with Fundamentals Puzzler: A Stupid Dream

May 5, 2013

Assume there’s no friction on the track and kitty has perfect balance. From how high must Thrasher the Cat start to make it safely around the loop without falling off due to gravity?

Elisabeth Eitel

Finagle J. Wurme is getting ready to live one of his lifelong dreams — auditioning for a spot on David Letterman’s Stupid Pet Tricks.

Finagle’s been training his Siamese cat, Thrasher, to ride a skateboard and things are going well. He’s now ready to take Thrasher to the next level.

Machinedesign Com Sites Machinedesign com Files Uploads 2013 05 298 Fundy Puzzle 0

Finagle is busy constructing a short track with a loop built into the middle, for Thrasher to skateboard down on the big day. But he’s not sure how high he needs to build the starting ramp for Thrasher to make it safely around the loop on his board.

Together, Thrasher and his skateboard weigh 15 lb and the radius of the loop is 5 ft. Assume there’s no friction on the track and kitty has perfect balance.

How high must Thrasher start from to be able to make it safely around the loop without falling off due to gravity?

I think I've solved this ... show me the solution.

This puzzler was originally Fun with Fundamentals Problem 298.

About the Author

Elisabeth Eitel

Elisabeth Eitel was a Senior Editor at Machine Design magazine until 2014. She has a B.S. in Mechanical Engineering from Fenn College at Cleveland State University.