#regents physics

Scalars - quantities with magnitude (size) only.

Examples: mass, length - distance, depth, width, height, temperature, change, volume, energy, density, etc.

Vector - an arrow (on the simplest level). All arrows have size and direction.

Concurrent - acting on the same thing at the same time (usually when referring to force vectors). 

Resultant vector - vector sum of two/more vectors

Component vectors - vectors that are added together. They are parts of a whole resultant vector. 

“Resolving a vector” - breaking it up into components

Seven Vectors

Force

Acceleration

Velocity

Displacement

Momentum

Impulse

Fields (gravitational, magnetic)

There are two ways to add vectors - 

Graphical - draw the vectors to scale using a ruler and protractor

Mathematical - addition, subtraction, pythagorean theorem, trigonometry. 

COMPONENT VECTORS MUST TOUCH HEAD TO TAIL. 

Trigonometry - used to find angles & sides in a triangle. Angles are symbolized by greek letter theta, ϴ. Use sine ϴ, cosine ϴ, tangent ϴ. 

Equilibrium - forces acting concurrently that balance each other out. In short, the resultant is 0 newtons. 

Equilibrant - same size as resultant, but points in opposite direction.

X - Horizontal

Ax= 0 m/s^2

Vfx=Vix

Dx=VixT

Vix=Vicosϴ

Y - Vertical

Ay= -9.81 m/s^2

Vfy=Viy+AyT

Dy=ViyT+.5AyT^2

Vfx=Vix^2+2AyDy

Newton’s Laws

Law of Inertia - Objects in motion tend to stay in motion and objects at rest tend to stay at rest unless acted upon by an outside force. 

Inertia = mass, resistance to a change in motion

Fnet = mass*acceleration (m*a)

the Net Force is also known as the “resultant force” and the “unbalanced force.”

It is often listed in reference tables as a=Fnet/m

The units for any force are newtons, or kg*m/s^2

For every action (force), there’s an equal and opposite reaction (force), e.g., when you pull, there’s friction, when you throw something up, there’s gravity acting upon it. 

Types of Forces

Fg - Gravity... The mutually attractive pull between masses. 

Fn - Normal force... Perpendicular. It occurs when a surface pushes back.

Fa - Applied Force... Comes from some outside source like a person or machine. 

Ff - Friction... A resistive tug in the opposite direction of an object’s motion. 

Free Body Diagram

Two dimensional motion can be horizontal and vertical, or x and y motions, e.g., truck moving horizontally, ball thrown straight up. 

Types of 2-D Motion:

Projectiles, e.g., a soccer ball being kicked up

Uniform circular motion, e.g., a toy plane being whirled around

Types of Projectiles mentioned on this blog: 

Projectiles launched horizontally 

Projectiles launched at an angle above the horizontal

*I learned in such a way that air resistance is neglected for most instances

Conventional projectiles include: a tennis ball, a canon ball, a football, a baseball, an arrow, a bullet/gun 

*For gun/bullet scenarios, know that a muzzle is a a mouth or opening, and that the muzzle velocity is the the velocity of a projectile as it exits the launcher. 

Key Facts About Projectiles

The shape of a projectile’s path is parabolic.

The horizontal acceleration is 0 m/s^2, so the x velocity (Vx) is constant, assuming no air resistance.

The vertical acceleration is -9.81 m/s^2.

At the peak of a projectile’s motion, its vertical velocity is 0 m/s.

For Projectiles launched at an angle above the horizontal, the time of flight is impacted by - 

Air resistance

Gravity (if different)

Initial velocity

Launch angle