# Physics Lectures

Physic's lectures presented during 2016 MORT U sessions by Matthew Otey and Brian Holton

## Vectors

Plenty of measurements in physics require both magnitude and direction to be accounted for. These are called vectors, and are represented as arrows.

## Motion

Changes in an object's location or position over a period of time. Several measurements in motion are * vectors*:

- Displacement (from starting to destination point)
- Distance can be measured in feet or meters

- Velocity (speed with direction)
- Velocity can be measure in ft/s or m/s

- Acceleration (how quickly does the velocity change?)
- Acceleration can be measured in or

- There are a few types of motion
- Linear (1D, straight line)
- Parabolic (2D, including gravity)
- Rotational (turning around an axis)
- Circular (revolution, not rotation)
- Periodic (oscillations, back-and-forth)

## Forces

A mass of any kind requires an unbalanced force in order to change its motion(accelerate)

Forces are * vectors* that result in the motion of objects when they are unbalanced

Newton's Three Laws of Motion:

- Inertia: objects will remain in motion or at rest unless an unbalanced force acts on it.
- For every action, there is an equal and opposite reaction

Inertia is * not* a force. It is the natural tendency for objects to continue what they are doing

- Forces
- Applied (direct propulsion or contact)
- Tension (pulled)
- Friction (resistance)
- Normal (surface)
- Weight (gravity)

The force of friction depends on the surfaces in contact with each other.

Friction always opposes potential or occurring motion.

## Simple Machines

A machine to make a task easier to perform(?)

- Lever: Inclined plane.
- Wedge
- Screw

- Pulley: Wheel and Axle

- If an object is displaced by some force, when the work is accomplished. This is a vector measured in Joules

## Power

## Energy

A requirement in order to accomplish work (Joules)

- Mechanical (kinetic and potential)
- Nuclear
- Thermal (friction)
- Chemical

## Momentum

The tendency for an object to continue moving the way it is moving. This is a * vector* quantity.

Momentum is *always* conserved in collisions

Elastic collisions → kinetic energy is conserved

Inelastic collisions → ?

## Electricity

The flow of electric charge, particularly electrons, to power circuits and components.

Conductors allow charge to flow. Insulators prevent the flow of charge.

Generally, the electronic components we will be using will abide by Ohm's Law.

- V, Voltage - electrical potential - Volts
- I, Current - flow of electricity - Amps
- R, Resistance, material preventing flow - Ohms (Ω)

Fuses physically break to prevent overwhelming current from overheating/destroying a circuit.

Circuit breakers trip (turn off) when too much current flows through them

0.07 Amps is enough send the human body into cardiac arrest

## Gear Ratios

Using a CIM motor with a 10-tooth gear and a direct drive configuration, revolutions per second can be calculated by

With a 4[?]" wheel, inches per revolution can be calculated by

**Circumference** -

or

Gears connect to gears. Sprockets connect to each other via chain.

The speed of the edge of a spinning object given by the equation

Rotational speed is denoted by

or

The number of teeth on a gear is proportional to the radius

## Torque

denotes Torque in N-m (Newton Meters)

A force is a push or a pull Torque causes something to rotate As gear speed decreases, torque increases. Torque and speed are inversely proportional

## Center of Mass

Center of Mass for an arm is

## Pneumatics