Science chapter 3: motion and forces

physics

the study of matter and energy and the interactions occurring between them

Aristotle

dominated scientist for almost 200 years

Galileo Galilei

the great Italian scientist investigating Aristotle. he believed that the universe, the world, and living things as precious creation of God

Sir Issac Newton

perhaps the greatest genius of modern science

James Clerk Maxwell

led the discovery of the laws of electromagnetism and the harnessing of electricity in daily life

classical physics

the branches of physics developed before 1900, including mechanics, thermodynamics, optics, acoustics, and electromagnetism

Albert Einstein

revolutionized the of motion and gravity with his theory of relativity

modern physics

the more recent contributions to physics including quantum mechanics, relativity, solid-state physics, and particle physics

scale quantity

has only a magnitude

vector quantity

has both magnitude and direction

distance

a scalar representing the total length of an object’s path

Displacement

a vector representing an object’s change in position

delta (Δ)

the Greek capitol letter that is used to represent the change in a value

vector addition

the combination of two different vectors

resultant

a vector showing a combined effect of two or more other vectors

collinear

vectors that are in the same direction or in opposite directions

Pythagorean theorem

the square of hypotenuse is equal to the sum of the squares of the legs

hypotenuse

the long side of the right triangle

motion

when an object changes positions

Dynamics

the study of motion and force

mechanics

the branch of physics that addresses the effects of force on matter

speed

a measure of how quickly an object moves

instantaneous speed

the speed of a moving object at any given instant

velocity

the position divided by time

acceleration

any change in velocity

deceleration

acceleration opposite the direction of motion

frame of reference

the space relative to which motion is measured

Galileo Galilei

recognized that motion can be described in terms of speed, velocity, and acceleration and that forces determine how objects move

Sir Isaac Newton

presented his findings to the world in his book mathematical principals of natural philosophy

principia

Newton’s book

force

the pushing or pulling actions of one object upon another

first law of motion

the velocity of an object is acted upon by an external force

inertia

the tendency of matter to resist changes in motion

law of inertia

the first law of motion

second law of motion

states that the force force required to accelerate an object at a certain rate equals the object’s mass times the desired acceleration

Newton

the SI unit of force

third law of motion

for every action there is an equal and opposite reaction

net force

the resultant of adding the individual forces on the object through the vectors addition

free-body diagram

represents the object and the forces on it without considering the causes of the forces or the reaction forces exerting by the object

law of universal gravitation

any two objects that attract each other through gravitational force

gravitational constant

a fixed number

weight

the gravitational pull on an object

gravity

the gravitational force exerted on an object near the surface of the earth or any celestial body

Galileo

the first to demonstrate that the acceleration caused by the earth’s gravity is independent of an object’s mass

acceleration of gravity

varies slightly from place to place

terminal velocity

the velocity of an objects will stop speeding up

centripetal force

causes the object to travel in a straight line

centrifugal force

weight that attempts to travel in a straight line, it’s inertia causes a pull on the strings and your hand

pendulum

an object that hangs from a fixed point and swings back and forth because of gravity

friction

the resistance arising to an object’s motion through a fluid or across to an object’s motion through a fluid or across a surface

kinetic friction

affects sliding objects already in motion

static friction

affects stationary objects, preventing them from moving at all