Newton's Cradle — Reading Comprehension

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This 4th-grade reading passage introduces students to the fascinating physics behind the classic desk toy, the Newton's Cradle. It aligns with the Next Generation Science Standards (NGSS) Disciplinary Core Concept PS3.B: Conservation of Energy and Energy Transfer. The passage explains how motion and energy are conserved and transferred from one ball to the next through a simple chain reaction. Key terms like potential energy and kinetic energy are defined in easy-to-understand language. Students will learn that when one ball is lifted, it gains potential energy, which is converted to kinetic energy as it swings down. This energy then transfers through the other balls, causing the last ball to swing out. The passage also includes a fun fact about the toy's history and its connection to Sir Isaac Newton. This resource is designed to make complex physics concepts accessible and engaging for elementary students. The included assessment questions test students on recall, inference, and application of the concepts presented.

CONTENT PREVIEW

Have you ever seen a Newton's cradle? It's that cool desk toy with five shiny metal balls hanging in a row. It might look simple, but it's a great way to see how energy and motion work!

What is a Newton's cradle? It's a device that shows conservation of momentum and conservation of energy. Don't worry, those are just fancy ways of saying that energy and motion don't disappear—they just move from one place to another. The balls are all the same size and weight, and they hang from a frame. When they are at rest, they are all touching each other.

To start the fun, you pull one of the end balls back and let it go. When you release it, the ball swings down and strikes the ball next to it. But what happens next is the amazing part! The first ball stops, but the very last ball on the other end swings away. The balls in the middle don't move at all! Why does this happen?

It's all about energy transfer. When you lift the first ball, you are giving it potential energy. This is stored energy because of its position. As the ball swings down, that potential energy turns into kinetic energy, which is the energy of motion. Right before the ball hits the one next to it, it has its maximum kinetic energy.

When the first ball hits the second ball, it transfers all of its kinetic energy to it. The second ball then transfers that energy to the third ball, and so on, all the way down the line. It's like a chain reaction! The energy travels through the balls, and since the energy has to go somewhere, it pushes the very last ball away from the group. That last ball now has the same amount of kinetic energy that the first ball had, which is why it swings up to almost the same height.

This process keeps happening. When the last ball swings back and hits the row of balls, the energy transfers back the other way, and the first ball swings out again. The sound you hear when the balls hit is a little bit of that energy being lost as sound energy, which is why the balls will eventually stop swinging.

Fun Fact: The device is named after Sir Isaac Newton, but he didn't actually invent it. It was created by an English actor named Simon Prebble in 1967. However, it perfectly demonstrates Newton's laws of motion

What kind of energy does a ball have when it is swinging?

stored energypotential energykinetic energylight energy

How many balls typically make up a Newton's cradle?

three ballsfour ballsfive ballssix balls

Why does the last ball swing away after the first ball hits?

The energy from the first ball transfers throughThe balls are attracted to each otherThe middle balls push the last ball awayThe sound causes the last ball to move

If you lifted two balls and let them go, what would likely happen?

Only one ball on the end would swing outThe middle balls would swing outThe balls would stop swinging immediatelyTwo balls on the opposite end would swing out

Based on the passage, what can we infer about sound?

Sound is not a form of energySound is a type of light energyThe sound of the balls hitting is energyThe sound is what makes the balls stop

A student lifts a ball higher. What effect will this have?

The ball will stop immediatelyIt will transfer more kinetic energyThe balls will make a quieter soundThe balls will not move

Imagine a Newton's cradle with ten balls. How does the energy transfer?

Only the first and last balls moveThe energy travels through all the ballsThe middle balls absorb all the energyThe energy gets stuck in the fifth ball

If the balls were all different sizes, how might the transfer be different?

The energy would not transfer at allThe larger balls would move fasterThe transfer would be less efficientIt would not make any difference