What is Newtons Cradle?
Newton’s Cradle is a device used to demonstrate conservation of momentum and kinetic energy. It consists of a series of identical balls, usually five or seven, each attached by two strings of equal length to a frame and just touching each other. Newton’s Cradle, first manufactured in 1967, is a popular desk toy. The device is so named because it demonstrates laws of physics discussed in Sir Isaac Newton’s 1687 work, Philosophiæ Naturalis Principia Mathematica. However, 17th century French physicist Abbé Mariotte was the first to demonstrate the law of impact between bodies that governs the movement of a Newton’s Cradle. To use a Newton’s Cradle, the first ball on one end of the device is picked up and dropped. It transfers energy through the middle balls before causing the ball on the far end to swing up. When the ball descends, the action repeats. The middle balls do not apparently move, while the two on the ends clack up and down. A similar effect can be seen if two or three balls ar
• What does it look like? • Why does it work? This lesson will answer those questions. There is a mini-quiz near the end of the lesson. Newton’s CradleNewton’s Cradle consists of several metal balls (usually 5) suspended from a rack by wires or rods, such that they line up and are in contact when in a resting position. There are two wires attached to each ball to keep the pendulum motion in one plane.End balls move When an end ball is pulled up and let go, it swings down as a pendulum and hits the next ball. The energy and momentum from that ball is transmitted through the three balls at rest to the ball on the other end. That ball is propelled forward at the same speed as the first ball had due to the force of the first collision. If two or more balls are pulled up and let go, the same number of balls will be propelled forward due to the collision.Slowly slows down Since it is a form of pendulum, the action will go back and forth until it slowly slows down due to losses from friction
