Physics is the…
Basic of all sciences. Its concepts are the foundation for all other sciences.
Mathematics is important to science because…
It gives a simple way to express complex relationships. It is unambiguous.
Difference between science and technology.
Science is a method of answering questions. Technology is a method of solving problems.
Fact
a close agreement by competent observers who make a series of observations of the same phenomenon
Law or Principle
A hypothesis that has been tested over and over again and is not contradicted
Theory
a synthesis of a large body of information that includes well-tested and verified hypotheses
Physics
The study of the nature of things such as motion, forces, energy, matter, heat, sound, light, and the composition of atoms
Why are equations often used in science?
Because they provide guides to thinking. They don’t have double meanings and provide a common language for the discussion of ideas.
Five general steps of the scientific method?
- Identify the problem.
- Create a hypothesis (an educated guess) about the answer.
- Predict the consequences of the hypothesis.
- Perform experiments to test your predictions.
- Formulate the simplest general rule that organizes the hypothesis, prediction, and experimental outcome.
1kg=
10N
10N=
2.2lbs
Vector quantity
A vector quantity is a quantity that describes both magnitude and direction.
Equilibrium rule
Whenever the net force on an object is zero, the object is said to be in mechanical equilibrium.
Two forces acting on a book at rest on a table
The weight of the book due to gravity acts downward. The support force provided by the table acts upward on the book.
Force
A push or pull on an object. Unit of force is N (newtons of gravity force).
Net force
The combination of all acting forces
When is something in equilibrium?
If an object moves at constant speed in a straight line then it is in equilibrium
Inertia is a way to measure…
how hard it is to change an object’s motion.
Mass
a measure of the amount of matter in an object. Unit of mass is kg.
Weight
A measure of the force of gravity on an object.
Equation relation to weight and mass.
Weight = mass * acceleration due to gravity. W=mg
Equation Newton’s second law of gravity
F=ma
(force = mass * acceleration). [kg * m/s^2]
m/s^2 =
N/kg
Newton’s first law.
Law of Inertia. A body in motion tends to remain in motion if no net force is exerted on the body in the direction of motion.
Copernicus’s idea
He thought that Earth and the other planets moved around the sun.
What did Galileo explain?
that a force is not necessary to keep an object moving
Friction
The force that acts between materials that touch as they move past each other. Irregularities in the surface that the object is touching obstructs motion and causes friction, which opposes motion.
What is a measure of inertia?
Mass. The more mass an object has, the more inertia it has and the more force is needed to change the state of motion.
A hypothesis must be…
testable. If it cannot be proven or disproven, it is outside the realm of science.
Tension
Stretching force
Scalar quantity
Can be described by magnitude only and has no direction.
Support force
Upward force that balances weight of an object on a surface. aka normal force.
Resultant
Sum of 2+ vectors
Acceleration
Means speed up, slow down or change direction. The rate at which velocity changes. Acceleration is around 10m/s^2 moving upwards, 9.8m/s^2 moving downwards
Speed
How fast something freely falls from rest after an elapsed time. Has both scalar and vector quantities.
Equation for falling in free fall (distance)
d = 1/2*gt^2. g=10m/s^2
Change in position
Motion
Change in motion
speed, velocity (w/ directional information)
Instantaneous speed
the speed at any instant.
Free fall
When an object moving under the force of only gravitational force
Elapsed time
The time passed since the beginning of any motion.
The instantaneous speed of an object at its highest point after it is thrown straight up into the air
zero
Distance
how far an object has fallen
Relative
when an object moves in motion with respect to the other object.
Speed equation
speed = distance/time. v = d/t
Average speed
ave. speed = (total distance covered)/(time interval)
Velocity
Speed in a given direction
Acceleration equation
acceleration = change of velocity/time interval
instantaneous speed equation
instantaneous speed = acceleration * elapsed time. v = gt
Vertical Direction velocity
(change in)y = v(0) + 1/2(a(y)t^2))
Horizontal direction change
(change in)x = v(0)t + 1/2(a(x)t^2))
Displacement
s = v(i)(change in)t + (a(change in)t)^2/2 s = distance
