Phys Ed

PHYS ED: Mythbusters – Newtons 3rd Law

An interesting way to explore and explain Newtons 3rd Law: If birds in a truck fly, does the truck get lighter?

http://kwc.org/mythbusters/2007/04/episode_77_birds_in_a_truck_bi.html

http://www.yourdiscovery.com/video/mythbusters-top-10-birds-in-a-truck/

My brother explained it as follows: You’ve got molecules of air in between the birds wings and the truck. The only way the birds can push off the ‘ground’ (ie. fly) is by producing enough force on these molecules to create sufficient lift. This force/lift is proportional to the mass of the birds because gravity is constant. This force/lift acts on the body of the truck. In other words, the lift caused by the bird’s wings exerts a downward force on the truck. This force is equal to their (the birds) mass… times acceleration due to gravity.

However, it depends on whether the truck is closed. If not, some of the force caused by the bird’s wings can go off the truck. If it was not, imagine you are walking under a bunch of birds and you should feel they are pushing you down.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s