The Science of Motion Cool Dudes of Science!

Aristotle From the Louvre

Lived from BCE (Greek) Lived from BCE (Greek) Used logic to theorize that things fell to earth so therefore the earth was the center of the universe Used logic to theorize that things fell to earth so therefore the earth was the center of the universe Falling objects fell at a speed proportional to their weight Falling objects fell at a speed proportional to their weight Ideas shaped scientific thought for 2000 years! Ideas shaped scientific thought for 2000 years! Aristotle

Copernicus

Copernicus Lived Lived Using careful observations and math, he reasoned that the earth moved around the sun Using careful observations and math, he reasoned that the earth moved around the sun

Galilieo Galilei Considered the “father of science” Considered the “father of science” “All truths are easy to understand once They are discovered; the point is to discover them.”

Galileo Lived Lived First to prove that Aristotle was wrong about falling objects First to prove that Aristotle was wrong about falling objects He dropped 2 cannon balls from the Leaning Tower of Pisa, one 10x heavier than the other. What would Aristotle have predicted? He dropped 2 cannon balls from the Leaning Tower of Pisa, one 10x heavier than the other. What would Aristotle have predicted? The two balls hit at the same time!! The two balls hit at the same time!!

Falling Objects If Galileo was right, why don’t sheets of paper and paper clips hit the ground at the same time? If Galileo was right, why don’t sheets of paper and paper clips hit the ground at the same time? Air resistance will slow objects down. In the absence of an atmosphere all objects, regardless of mass, will fall at the same rate. Air resistance will slow objects down. In the absence of an atmosphere all objects, regardless of mass, will fall at the same rate. hammer and feather on the moon hammer and feather on the moon hammer and feather on the moon hammer and feather on the moon

Sir Isaac Newton Newton’s Laws Newton’s Laws

Newton Lived from Lived from Came up with universal law of gravitation Came up with universal law of gravitation Came up with laws of motion Came up with laws of motion

Gravity Universal Law of Gravitation: The force of gravity acts between all objects in the universe Universal Law of Gravitation: The force of gravity acts between all objects in the universe Strength of force depends on: Strength of force depends on: Mass - the bigger the object’s mass, the more force or pull it produces Mass - the bigger the object’s mass, the more force or pull it produces Distance- the closer together, the bigger the pull. Distance- the closer together, the bigger the pull. F= (mass of object 1 x mass of object 2) / r 2 F= (mass of object 1 x mass of object 2) / r 2 where r=the distance between the objects

Gravity Gravity is an attractive force Gravity is an attractive force Acceleration due to gravity is 9.8m/s 2 Acceleration due to gravity is 9.8m/s 2 Air resistance is friction with the air, it opposes gravity Air resistance is friction with the air, it opposes gravity Mass – the amount of matter in an object Mass – the amount of matter in an object Weight- the measure of the force of gravity on an object Weight- the measure of the force of gravity on an object

Terminal Velocity! The maximum velocity a falling object can achieve. The air resistance equals the force of gravity so the object does not accelerate any more.

1 st Law of Motion- Inertia An object at rest stays at rest, an object in motion stays in motion, unless an outside force acts upon it. An object at rest stays at rest, an object in motion stays in motion, unless an outside force acts upon it.

2 nd Law of Motion F=ma The net force on an object is equal to the product of its mass and acceleration The net force on an object is equal to the product of its mass and acceleration Force = mass x acceleration Force = mass x acceleration m 1 x a 1 = m 2 x a 2 m 1 x a 1 = m 2 x a 2 (big) (little) = (little) (big) (big) (little) = (little) (big)

3 rd Law of Motion = & opposite For every action there is an equal and opposite reaction For every action there is an equal and opposite reaction Example: When you let a balloon go, the air rushing out the end forces the balloon in the opposite direction. The greater the rush of air, the faster the balloon moves Example: When you let a balloon go, the air rushing out the end forces the balloon in the opposite direction. The greater the rush of air, the faster the balloon moves

Friction & Force Force: a push or a pull that is exerted on an object and gives the object energy to start moving, or change direction. Force: a push or a pull that is exerted on an object and gives the object energy to start moving, or change direction. Friction: A force that opposes the motion of an object. Friction: A force that opposes the motion of an object. Types: sliding, rolling, fluid Types: sliding, rolling, fluid

Friction Which object below encounters more friction? Why? Which object below encounters more friction? Why?

Measuring Force One unit used to measure force is called the Newton One unit used to measure force is called the Newton A Newton (N) is defined as the metric unit of force needed to move a 1 kg mass 1 m in 1 second A Newton (N) is defined as the metric unit of force needed to move a 1 kg mass 1 m in 1 second