Ch.5 Physics (Important Ch notes) Flashcards
The higher the mass of something, the more the weight of it is
The difference between Mass and Weight:
The mass is the amount of matter in an object.
The weight is the pull of gravity on an object.
What are the 3 states of matter:
Solid, Liquid and Gas
Anything w/ matter has mass and volume
Specific Gravity tells you whether something is floating or sinking in water (An object above 1 will sink in water)
The same formulas used for Specific Gravity are used to find the Density of gases by substituting air or hydrogen for water
What are the 3 types of friction:
Static friction, Sliding friction, Rolling friction
5 ways in how simple machines are used:
- To transfer energy like in a generator transforming mechanical energy in electrical energy
- To transfer energy from one place to another like connecting rods, crankshaft, and reduction gears to transfer energy from an aircraft engine to its propeller
- To multiply force, a system of pulleys used to lift a heavy load
- To multiply speed, like a bicycle by which speed can be gained by a greater force
- To change the direction of a force, like a flag hoist, a downward force on one side of the rope exerts an upward force on the other side, raising the flag toward the top of the pole
What are the 6 types of Simple Machines:
The Lever
The Pulley
The Wheel and Axel
The Inclined Plane
The Screw
The Gear
The wheels in pulleys are sometimes referred as the “Sheave” or the “Sheaf”
The frame that supports the wheel in a pulley is called a “Block”
With Gears, the one with the input force is called the “Drive Gear” and the other one is called the “Driven Gear”
Bolts, Screws and Wedges are examples of devices that operate on the principle of the Inclined plane
What are the 5 types of Stress
Shear
Tension
Bending
Compression
Torsion
The difference between Speed and Velocity
Speed refers to how fast an object is moving or how far the object will travel in a specific time.
Velocity tells the speed and direction of an object.
Load is same as Resistance
Work is described as a force acting through a distance
Potential Energy is classified in 3 groups
- Energy due to position
- Energy due to distortion of an elastic body
- Energy which produces work through chemical action
Fulcrum is where things can balance, move, pivot
The difference between Gas and Liquid
Gas can be compressed and liquid can’t
Newtons 1st Law
An object at rest remains at rest, an object in motions remains in motion at constant speed.
Also known as Inertia
Example: When an airplane is brought to a sudden halt in the parking area and the passengers are thrown forward in their seats
Newtons 2nd Law
A body that has great momentum (motion) has a strong tendency to remain in motion and is therefore hard to stop
Example: A train moving at a low velocity is difficult to stop because of its large mass
Newtons 3rd Law
For every action there is an equal and opposite reaction
Example: When you jump, your legs apply a force to ground and the ground applies an equal and opposite reaction force that propels you into the air
Heat may also be defined as the total kinetic energy of the molecules of any substance
Energies that can be converted into heat energy:
Mechanical Energy
Electrical Energy
Chemical Energy
Radiant Energy
Nuclear Energy
Sun
The hotter the body the more kinetic energy is possessed, the cooler the less
3 ways heat can be transferred:
Convection
Conduction
Radiation
Water has a high heat capacity
Solids will expand when heated and contract when cooled, as in the atoms will separate and connect
Sound travels faster through water than it does through air at the same temp
Engine power output is calculated on dry air
The 4 forces of flight: (All measured in lbs)
Lift
Weight
Thrust
Drag
As the boundary layer approaches the center of the wing, it begins to lose speed due to skin friction and it becomes thicker and turbulent. Here it is called the turbulent layer. The point at which the boundary layer changes from laminar to turbulent is called the transition point. Where the boundary layer becomes turbulent, drag due to skin friction is relatively high. As speed increases, the transition point tends to move forward. As the angle of attack increases, the transition point also tends to move forward. With higher angles of attack and further thickening of the boundary layer, the turbulence becomes so great the air breaks away from the surface of the wing. At this point, the lift of the wing is destroyed and a condition known as a stall has occurred
Example on page 198 for figure 5-58
The center of gravity is also referred to as the center of rotation.
5 Types of Aircraft stability:
Static Stability
Dynamic Stability
Longitudinal Stability
Lateral Stability
Directional Stability
4 Types of Tabs
Trim tabs
Anti-servo tab
Balance tab
Servo tab
To give the wing the ability to produce maximum low speed lift without being drag prohibitive, retractable high lift devices, such as flaps and slats, are utilized.
Transonic flight is the most difficult flight regime for an airplane, because part of the wing is experiencing subsonic airflow and part is experiencing supersonic airflow
Helicopter Aerodynamics -
The helicopter, as we know it today, falls under the classification known as rotorcraft. Rotorcraft is also known as rotary wing aircraft, because instead of their wing being fixed like it is on an airplane, the wing rotates. The rotating wing of a rotorcraft can be thought of as a lift producing device, like the wing of an airplane, or as a thrust producing device, like the propeller on a piston engine.
For a subsonic airfoil, the aerodynamic center, or the point of support, is approximately 25 percent of the way back from the wing leading edge. In supersonic flight, the aerodynamic center moves back to 50 percent of the wing’s chord, causing some significant changes in the airplane’s control and stability
What’s the specific heat of water?
1.000
What’s the specific heat of mercury?
0.033
Types of Density Altitude:
Indicated Altitude
True Altitude
Absolute Altitude
Pressure Altitude
Density Altitude
The 4 forces of flight:
- When an airplane is accelerating, it has more thrust than drag
- When an airplane is decelerating, it has less thrust than drag
- When an airplane is climbing, it has more lift than weight
- When an airplane is at constant altitude, loft and weight are equal
Stall can happen at any speed
The center of gravity is in front of the center of lift because you want the aircraft to be able to pitch down
Shifting Ailerons allow control over roll in lateral stability
Standard temperature at sea level:
15 degrees celsius
Press altitude is corrected for non standard temperature variations
(Cool air is more dense than warm air, so pressure over an area of cool air is higher than an area of warmer air. Pressure changes throughout the day as temperatures increase and decrease, so it’s important to periodically update the altimeter setting in an aircraft to make sure the altitude shown is accurate.)
Temperature lapse rate:
2 degrees celsius per 1,000 feet
Heat, humidity and altitude affect density altitude
The higher the density altitude, the better the aircraft performance. The lower the DA, then the weaker the performance
Example of Density Altitude can be found on project 05 on procedure 2
Pressure is typically measured in psi, but other units include inches or millimeters of mercury and millibars
Static is how fast the aircraft takes to recover
Why does increasing the temp of a gas decrease its density ?
The volume increases, so there’s ;less mass per unit volume
Water vapor is less dense than air
Differential pressure is the difference between pressures being read at 2 different locations
An airplane will have to fly the fastest to produce the required lift under which atmospheric conditions?
High Temp and High Humiditiy
Relative Humidity is expressed as a percentage and is based on what?
The prevailing air temp and pressure
An atmosphere with 20% water vapor will weight the most
(Less water vapor will cause more weight but more water vapor will weight less)
An atmosphere with 20% water vapor will weight the most
(Less water vapor will cause more weight but more water vapor will weight less)
If the pressure on a confined liquid is doubled then the volume will remain the same
What happens when a fluid flows theough a convergent shape (consider subsonic speed)
The velocity of that fluid will increase and the pressure will decrease
What happens when a fluid flows theough a divergent shape (consider subsonic speed)
The velocity will decrease and the pressure will increase
