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Newton's Third Law

For every action, there is an equal and opposite reaction.

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Practice Newton's Third Law

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The Art of Falling

The Art of Falling

Credit: The U.S. Army
Source: http://www.flickr.com/photos/soldiersmediacenter/2990718614/

After jumping out of a plane that is flying 10,000 ft above the surface of the Earth, this skydiver reached up to 120 mph before deploying their parachute. Within a matter of seconds the increased surface area allows the pair’s velocity to be slowed to a safe velocity for landing. By using Newton’s 2nd law, you can easily calculate what speed this pair landed at.

New You Can Use

• Since the early 1100s, people have been using parachutes to skydive. Even though they didn’t know it, they were using the most basic principles of physics. By using a parachute the effective surface area of the falling body is increased allowing for more air to be “caught”.
• Effectively designed parachutes will expose a skydiver to 3-4Gs of negative acceleration when the chute is deployed. This causes the skydiver’s velocity to go from 120 mph to roughly 18 mph in a matter of seconds. With the forces balanced, the skydiver will be able to safely land.

Show What You Know?

Using the information provided above, answer the following questions.

1. When the skydiver is falling at a constant velocity after the parachute is open, what is their acceleration?
2. Explain why it is not advised to use a parachute that is a big as possible, assuming you could safely deploy it?
3. At what point in the skydiving experience is the acceleration due to gravity equal to zero?

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