What's the BIG Idea?: Amazing Science Questions for the Curious Kid

What's the BIG Idea?: Amazing Science Questions for the Curious Kid — page 9
4 What’s the Big Idea Four hundred years ago an Italian mathematician Galileo Ga-li-LAY-oh 1564 1642 did a thought experiment about this He concluded that rolling balls should never stop rolling That they do didn’t make sense to him Do Galileo’s thought experiment yourself use your imagination to see why Check it out Imagine how a ball rolls up a hill after you give it a little push It rolls slower and slower until it stops for a moment then rolls back downhill Now imagine how the ball rolls downhill It goes faster and faster Think about this If the ball rolling uphill slows down and the ball rolling downhill speeds up how should it roll if there is no hill A ball rolling on level ground should not speed up or slow down It should go at the same speed forever