Question

what is newtons first law

Answer 1

HE SAYYYS....that things that aren't moving will stay still,
and things that ARE moving will keep moving,
UNLESS an "unbalanced force" (something weird) intervenes, and changes all that.

Answer 2

Newton's first law is sometimes called "the law of inertia".
He basically states that an object at rest will stay at rest and an object in motion will stay in motion with the same speed and in the same direction unless acted upon by an imbalanced force.

So think of an aeroplane. If nobody's flying the aeroplane (so it is at rest) , it's engines would not be turned on right? So therefore it would not move and it would stay at rest right? :)

But if the aeroplane was flying in the air at a constant altitude, then the "drag" (Drag is the force that acts opposite to the direction of motion. Drag is caused by friction and differences in air pressure) and "thrust" (force that propels a flying machine in the direction of motion, so forward direction. Engines produce thrust) are EQUAL so then the aeroplane will have a constant air speed.

If we INCREASE "thrust", then the aeroplane will speed up and drag will also increase.
BUT once drag is equal to thrust, it will again mean that the aeroplane travels at a constant airspeed again :)

Here's a link which provides the aeroplane example if you want to read about it : http://www.grc.nasa.gov/WWW/k-12/airplane/newton1.html