Newton's Laws

By: Juliette M. Sierra

Newton's 1st law

An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Ex .A.Have you ever experienced inertia (resisting changes in your state of motion) in an automobile while it is braking to a stop? The force of the road on the locked wheels provides the unbalanced force to change the car's state of motion, yet there is no unbalanced force to change your own state of motion. Thus, you continue in motion, sliding along the seat in forward motion. A person in motion stays in motion with the same speed and in the same direction ... unless acted upon by an unbalanced force of a seat belt.

Ex.B.Blood rushes from your head to your feet while quickly stopping when riding on a descending elevator


Newton's 2nd law

The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.

Ex.C.NASA rockets (and others) accelerate upward off the launch pad as they burn a tremendous amount of fuel. As the fuel is burned and exhausted to propel the rocket, the mass of the rocket changes. As such, the same propulsion force can result in increasing acceleration values over time.

Ex.D. If you push twice as hard on a car, it will go twice as fast.

Newton's 3rd law

For every action there's an equal and opposite reaction.

Ex.E.While driving down the road, a firefly strikes the windshield of a bus and makes a quite obvious mess in front of the face of the driver.

Ex.F.A bird pushes air down while flying (action), Since forces result from mutual interactions, the air must also be pushing the bird upwards (equal and opposite reaction). This allows the bird to fly :)