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Head First Physics by Heather Lang

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Chapter 11. Weight and the normal force: Forces for courses

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Sometimes you have to make a statement forcefully. In this chapter, you’ll work out Newton’s 2nd Law from what you already know about momentum conservation to wind up with the key equation, Fnet = ma. Once you combine this with spotting Newton’s 3rd Law force pairs, and drawing free body diagrams, you’ll be able to deal with (just about) anything. You’ll also learn about why mass and weight aren’t the same thing, and get used to using the normal force to support your arguments.

WeightBotchers are at it again!

WeightBotchers claim that their new product guarantees instant weight loss. It’s been difficult to miss their brash advertisements since the campaign launched last week.

But the TV show FakeBusters doesn’t buy those claims, and want you to investigate the details. If you can prove that the WeightBotchers machine is a hoax, your work will be featured in a special episode in their next series.

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Is it really possible to lose weight instantly?!

Here’s the deal. The machine has a platform at the top with some scales on it. When you stand on the scales, they read the same number of kilograms as they usually would in your bathroom. No surprises there.

But then the platform you’re standing on suddenly moves downwards - and the reading ...

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