# Toy given to einstein

i heard this story a while back:

einstein was given a toy by one of his long time friends. it was a little ball with a string attached. the objective of the toy was to get the ball on the string to sit on the rod... here's a picture that looks like the toy i remembered in the photo:

http://www.allynhouseinnauvoo.com/store_images/1162918679.jpg

einstein immediately knew the trick and was able to get the ball on the rod. i think it had something to do with one of his discoveries but im not sure. what is the trick and why did thsi friend give him the toy in the first place? I heard this a while back but was never able tofigure it out

mgb_phys
Homework Helper
Never heard that - the normal story is that he was given a (magnetic) compass and that led to his interest in physics. It might be one of those Newton+Apple stories, I don't remember reading it in Pais's biography.

there's a photo of him and his friend and he has that toy in his hands, i cant seem to find it... but i remembered this from long ago since i've always wondered how he was able to immediately figure out the trick

Danger
Gold Member
It looks a lot like something that I had as a kid. It's not just a stick; there's a ball-size hemispherical cavity in the end. The idea is to get the ball to land in it and stay there. The trick is to pull the stick in the direction of ball movement at contact to prevent bouncing.

It looks a lot like something that I had as a kid. It's not just a stick; there's a ball-size hemispherical cavity in the end. The idea is to get the ball to land in it and stay there. The trick is to pull the stick in the direction of ball movement at contact to prevent bouncing.

you have a scary avatar

Danger
Gold Member
Thank you. That's me in the picture.

rcgldr
Homework Helper
That's the "easy" version of that toy. A similar toy has a peg on the stick, and the hole in larger ball, and requires the ball be accelerated straight up and then the peg on the stick inserted into the hole while the ball is in mid-air. It wasn't that difficult to do though. The cup and ball version was easy in that you could pull the ball straight up or swing it in an arc and still catch it in the cup since the ball's rotation isn't an issue. It's the 3rd toy (bilbo catcher) on this web page, the hole in the ball opposite the string end isn't visible in the picture:

http://www.historylives.com/toysandgames.htm

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That's not the toy. There is a discussion of it in the book "The Old Man's Toy" by A. Zee. I don't remember the exact construction, but it did have a spring attached to the ball. The solution was to
drop it. Gravity would neutralize all the forces except the spring force.