Unbalanced Forces Notes #1

Newton’s 1st law! Objects in motion...

Mass resists acceleration

ExampleFull shopping cart vs. empty shopping cartThe greater the mass the more force it takes

to accelerate the object Acceleration is inversely proportional to

massAcceleration ~ 1

massAs the denominator increases the wholequantity decreases

Ten times as much

Newton’s Second Law The acceleration produced by the force

on an object is directly proportional to the magnitude of the net force, is in the same direction as the net force and is inversely proportional to the mass of the object

Mathematically: acceleration~ net force mass

Newton’s 2nd Law in Mullisen’s words... The harder you push, the faster it

accelerates – BUT – if it’s massive, it doesn’t accelerate as much.

Acceleration = How hard you push

How massive it is

acceleration = net force mass

Baby Hippo Physics You throw a baby hippo upward with a force of

1000 Newtons. The baby hippo’s mass is 500 kg

Acceleration ? = 1,000 newtons up

500 kilograms

Answer: 2 m/s/s

From the beginning of your throw to the end of your throw (which took 1 second), the baby hippo accelerated from 0 m/s to 2 m/s

Baby Hippo Physics

Now you strap the baby hippo to a rocket. The rocket burns for 12 seconds, and propels the baby hippo with a force of 3,000 Newtons.

Acceleration = 3,000 N

500 kg Answer: a = 6 m/s/s Every second the rocket burns, the baby

hippo goes 6 m/s faster. After 12 seconds, he’s going 72 m/s (161 mph)

Baby Hippo PhysicsNow you throw the baby hippo’s mom upward with a force of 1,000 Newtons. Her mass is 4,500 kg.

Acceleration ? = 1,000 newtons up

4,500 kilograms

Answer: a = .22 m/s/s

From the beginning of your throw to the end of your throw (which took 1 second), the mommy hippo accelerated from 0 m/s to .22 m/s

Newton’s 3rd Law of Motion For every action there is an equal and

opposite reaction. Examples:

You jump off a small boat.Oxygen tank in outer space. You sitting in your chair.JetLev Water Rocket Pack