Navy OAR Mechanical Comprehension

The wrapped incline plane on a screw is also called the ...

thread

Examples of third class levers

tweezers, shovels, fishing poles

Two types of current sources

Direct Current (DC) and Alternating Current (AC)

The nuclear force has a larger magnitude than the _________ that ________

The strong nuclear force has a larger magnitude than the electromagnetic force that pushes protons (positive charges) away from each other in the nucleus.

Inertia

The tendency of an object to resist a change in motion

The tension of pulleys is always equal to

The tension of pulleys is always equal to the weight it supports.

Weak Force

Force that is the key to the power of the sun; responsible for a process known as radioactive decay; Plays a role in nuclear reactions (like those in stars)

Non-Fundamental Forces

Forces that can be derived from the four fundamental forces

Equivalent resistance

Found by adding the resistance of each resistor (i.e. R1 + R2 + R3 ..... )

Which force opposes motion and describes the resistance of two surfaces in contact as they move across each other?

Friction

First class lever

Fulcrum in the middle; The fulcrum is between the input and output forces, and the input force is in the opposite direction of the output force

OTHER SIDE The gear that will mesh with Gear C needs to have the opposite orientation and be similar in size. The only gear that meets these conditions is Gear E. (C) Correct.

Gear C is intended to mesh with A. Gear A only. B. Gear B only. C. Gear E only.

OTHER SIDE The product of the number of teeth and the revolutions for each gear will be equal. 15(20)=10(r) [the number of rotations x the number of teeth = number of teeth on Gear 2 x R] r = 300/10 = 30 revolutions (A) Correct.

If Gear A makes 15 revolutions, Gear B will make A. 30 revolutions. B. 25 revolutions. C. 22 revolutions

If force and displacement are in opposite directions then the work positive or negative?

If force and displacement are in opposite directions then the work is negative (-) Ex: You throw a ball in the air and gravity pulls it downwards but it is moving upwards

If force and displacement are in the same direction then the work is positive or negative?

If force and displacement are in the same direction then the work is positive (+) Ex: Pushing something and it moves in the same direction

If the fulcrum is closer to the load, then less effort is needed to move the load. If the fulcrum is closer to the effort, then the load will move a greater distance.

If the fulcrum is closer to the load, then less effort is needed to move the load. If the fulcrum is closer to the effort, then the load will move a greater distance.

Example of work and power

If you lift a heavy object that is work. If you are holding the heavy object that is not work because the object is not moving any distance. Great power means a large amount of work or energy developed in a short time. For example, when a powerful car accelerates rapidly, it does a large amount of work and consumes a large amount of fuel in a short time.

In an atom, negatively charged _____ will orbit around positively charged ______.

In an atom, negatively charged electrons will orbit around positively charged nucleus.

Absolute zero is the lowest possible temperature, which is reached at zero ....

0 Kelvin is absolute zero

Semiconductors are _____ (insulators / conductors) unless dopants are added.

Semiconductors are insulator unless dopants are added.

Newton's Second Law of Motion

The acceleration of an object depends on the mass of the object and the amount of force applied AND Force = mass x acceleration where F is the sum of all the forces on an object

The pendulum is held at point A, and then released to swing to the right. At what point does the pendulum have the greatest kinetic energy?

The bottom of the arc must have the greatest kinetic energy because it is the point with the least potential energy, since the total energy is equivalent to the sum of both potential and kinetic energy.

If point A has a reading of 1,000 V and point B has a reading of 1,001, what is the potential difference (voltage) between points A and B?

The difference is only 1. Therefore, a charged particle moving from A to B would have much less kinetic energy than a charged particle moving from A to zero potential (a difference of 1,000 Volts)

The electric field has a direction and always moves away from ______ charges and toward _______ charges.

The electric field has a direction and always moves away from positive charges and toward negative charges.

Electromotive Force (EMF)

The electrical action produced by a non-electrical source, measured in volts

Valence Electrons

The electrons in the outermost shell (main energy level) of an atom; these are the electrons involved in forming bonds.

Are the electrons of an atom positive or negative?

The electrons of atoms are negative

Kinetic Energy

The energy an object has due to its motion; Any object in motion is using kinetic energy. For example, when you throw a baseball - when the baseball is "moving" that's the kinetic energy. Moving water and wind are also examples of kinetic energy. "Energy of movement"

Elastic Potential Energy

The energy of stretched or compressed objects Example: Compressing a spring, a bent diving board just before a divers jump, the twisted rubber band which powers a toy airplane.

Fulcrum

The fixed point around which a lever pivots

Conventional Current

The flow of positive charge

Electromagnetic Force

The force between electric charges;

Gravitational Force

The force that pulls mass together; The force of attraction between all masses in the universe

formula for force on a spring

The formula for force on a spring is F=-kx, with F representing force, k representing the spring constant, and x representing the displacement of the spring.

Third class lever

The fulcrum is at one end of the bar and the effort is between the fulcrum and the resistance; The load is opposite the fulcrum

The further away from the rotational axis the (easier / harder) is it to rotate the object?

The further away from the rotational axis the harder is it to rotate the object. https://www.youtube.com/watch?v=uyU25DdONjo&ab_channel=JamesDann%2CPh.D.

The greater the difference in the # of teeth in each gear, the greater the

The greater the difference in the # of teeth in each gear, the greater the torque and mechanical advantage

The higher the mechanical advantage the (better or worse) for the user?

The higher the mechanical advantage the better for the user.

Buoyant Force

The upward force experienced by floating objects

The vector of Buoyant Force always pushes in what direction

The vector of Buoyant Force always pushes up (Buoyant force is a vector that always pushes upwards)R

What has more mass, a proton or an electron?

There is more mass in a proton and the mass of an electron is almost 2,000 times lighter

Electrical Potential

The potential energy per unit of electric charge

Gear Ratio

The ratio of the speed of the driving member of a gear train to that of the driven member; How many times one gear turns compared to the gear it is touching

What is the RPM for a gear that has 8 teeth and makes two contacts a second?

Two contacts a second = 120 contacts a minute (60 x 2 = 120) 120/8 = 15 RPM

If there is not displacement (even with force - like pushing onto a wall) then work is/is not done?

Without force, and displacement in the same direction as the force, no work has happened

The SI Unit for Mass is the

kilogram (kg)

Sliding friction is also called

kinetic friction

Valence shells that are nearly empty will more easily ...

lose electrons

Equation for Gravitational Potential Energy

m = mass g = 9.8m/s^2 (remember mg is an object's weight) h = height

equation for kinetic energy

m = mass and v = speed

Static friction

a friction force that acts on objects that are not moving, overcoming static friction is when you push a box and it finally moves in the other direction "Static friction can be understood as the force acting between two things that are in contact with each other while not moving."

Electric Charge

a fundamental property of matter, like mass; It can be either positive or negative Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field.

Scalar

a measurement (physical quantity) that has size (magnitude) but no direction Examples: Speed, Distance, Mass SDM

OTHER SIDE Adjacent gears rotate in opposite directions, so Gears 2 and 4 will rotate in the opposite direction of Gear 3. (B) Correct.

Which of the gears are moving in the opposite direction of Gear 3? A. Gear 1 and Gear 4 only B. Gear 2 and Gear 4 only C. Gear 2 and Gear 5 only

An object in equilibrium will either be __________ or moving at _____________________.

at rest or moving at a constant velocity

Protons and neutrons have mass that is measured in _______

atomic mass units (amu)

Outside of nuclear reactions, protons and electrons are not ...

created or destroyed

Equation for current

current = charge / time

Electric Potential Energy

derived from the interaction between positive and negative charges Examples: a light switch or lightbulb that is turned off, your car's headlights before they are turned on, a radio tower that is not working, a cell phone that is turned off.

The charge of a proton is represented as ...

e

Current flow can more accurately be called the flow of Electrons or Protons?

electrons

The closer the string is to the center of the pulley, the

faster the pulley rotates

Three types of levers

first class, second class, third class

Work is measured in (not the SI unit)

foot-pound force (lbf)

A first class lever will have a mechanical advantage of ____ (if the fulcrum is exactly in the middle of the load and the input force)

1

A single pulley lifting a weight will have a mechanical advantage of ...

1

1 Newton =

1 kg m/s^2 The force required to accelerate 1 kilogram of mass at 1 meter per second

Pulley

A simple machine that consists of a rope that fits into a groove in a wheel; A simple machine that redirects force by supporting a rope that can move freely by rotating the pulley

Inclined Plane

A simple machine that is a straight, slanted surface; A simple machine (ramp) that reduces the amount of force needed to raise a mass to a certain height

Wedge

A simple machine that is an inclined plane that moves; A simple machine that converts an input force onto one surface into a force that is perpendicular to its other surfaces

Screw

A simple machine that is an inclined plane wrapped around a central cylinder to form a spiral; Converts rotational motion into linear motion

Gears

A simple machine with two or more wheels linked together by interlocking teeth

Semiconductor

A substance that can conduct electricity under some conditions; The atoms are neither full nor empty

kilowatt-hour (kWh)

A unit of measurement by which electricity is sold "Electric companies charge in terms of kilowatt-hour (kWh).

Newton's First Law

An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Rolling friction

friction that occurs when an object rolls over a surface, like a bowling ball rolling down the lane

An induction clutch works by

magnetism An induction clutch is a magnetic clutch. When a conductor (wire) is wrapped around a core and electricity is passed through the wire, it sets up a magnetic field. The same wire also acts as an inductor, which produces inductance, during AC current flow. It's similar to resistance in a resistor in that it resists current flow, but the value of inductance is based on the value of the inductor (written as L) and the frequency of the AC current. Therefore, an induction clutch employs magnetism to operate.

Dopants

impurities added to a semiconductor to increase conductivity

Resistance

includes the materials resistivity as well as the actual size of the device.; Measures the amount of current repulsion in a circuit

The purpose of an air valve in a heating system is to

B. relieve the air from steam An air valve on a radiator removes air from the steam pipes. If air is trapped in the pipes, it prevents the steam from going to the radiator. This would prevent the radiator from producing heat

Mechanical Energy

is caused by motion (kinetic energy) and position (potential energy) Examples: Elevators, wrecking ball, cars, hammer in motion

Friction

is created by two objects moving against each other

Mechanical Advantage

Ratio of the output force exerted by a machine to the input force applied to the machine. output force / input force

Non-Fundamental Forces (list)

tension, friction, the normal force, and the buoyant force

Ground wire

Connects circuits in the home to the earth, giving charges alternate path in case of a short circuit; Can literally be a wire that goes into the ground; Ground is at zero potential

What is the unit of charge?

Coulombs (C)

What does an ammeter measure?

Current (amps)

Current is positive in what direction of the flow of electrons?

Current is positive in the opposite direction of the flow of electrons.

Pressure

the amount of force exerted per unit area of a surface force/area

Electromagnetic Force is attractive when charges are

the charges are the opposite sign (positive-negative)

examples of conductors

copper, aluminum, gold, silver, steel, iron, seawater

A single pulley is attached to the ceiling. It is holding a rope that is attached to the floor on one side and a person of weight 100 N on the other. What is the tension in the rope?​ A. 0 N B. 50 N C. 100 N

(A) Incorrect. The tension will be equal to the weight it supports, 100 N (B) Incorrect. The tension will be equal to the weight it supports, 100 N. (C) Correct. The tension will be equal to the weight it supports, 100 N.

moment of inertia equation

(Moment of) I=mr^2 m is mass, r is distance the mass is from the rotation axis

The equation for determining rotations of side-by-side gears

(Ra)(Ta)=(Rb)(Tb) R is rotations and T is teeth The number of rotations for Gear A x the number of teeth on Gear A = The number of rotations for Gear B x the number of teeth on Gear B

The charge of an electron is represented as ...

-e

Centripetal Force

A force that causes an object to move in a circle

A charge of 14e means there are ...

14 protons providing that charge

1kWh=?J

3,600,000 J

Wheel and Axle

A simple machine consisting of two circular objects of different sizes; the wheel is the larger of the two circular objects; A simple machine that has a rotating structure with two different radii

At which of the points shown above is the basketball moving the fastest? ________C ____B______D A ____________ E

A and E An object traveling in an arc has a velocity of zero at the top of its path and is moving slower the closer it is to that point. The object will also have the same speed at both points on the path that have the same height. So, the ball will be moving the fastest at points A and E, since both have the same height and are farthest from the top of the arc. The speed is the same at points A and E, but the velocity is different. At point E, the velocity has a maximum negative value. Therefore, the speeds are the same at A and E but the velocity is higher at A.

Parallel Circuit

A circuit that contains more than one path for current flow.

Series Circuits

A current that has only one path

Fuse

A device that breaks the circuit (creates an open circuit) when too much current is flowing through it.

Alternating Current (AC)

A flow of electric charge that regularly reverses its direction.

Current

A flow of electric charge.

Which statement is true of the total energy of the pendulum? A. Its total energy is at a maximum and equal at Points A and E. B. Its total energy is at a maximum at Point C. C. Its total energy is the same at Points A, B, C, D, and E. D. The total energy can't be determined without knowing the pendulum's mass

A is wrong. Even though the total energy is at a maximum at Points A and E, it isn't equal at only those points. The total energy is the same at all points. B is wrong. The kinetic energy is at a maximum at C, but not the total energy. The correct answer is C. The total energy is conserved, so it's the same at all points on the arc. D is wrong. The motion of a pendulum is independent of the mass. Just like how all objects fall at the same rate, all pendulum bobs swing at the same rate, dependent on the length of the cord

A large amount of mass far away from the axis of rotation will have a larger moment of inertia (more resistant) than ....

A large amount of mass far away from the axis of rotation will have a larger moment of inertia than a smaller mass closer to the axis of rotation

Conductor

A material that conducts heat well because the atoms have nearly empty valence shells and electrons move freely

Insulator

A material that does not conduct heat well because it has a nearly full valence shell (meaning the electrons do not easily flow)

Conductivity

A material's ability to allow heat to flow

Resistivity

A measure of how easily an electron can move through a material; "A property of material that opposes electric flow (flow of charge)"

Mass

A measure of how much matter is in an object

Weight

A measure of the force of gravity on an object

Fixed pulley

A pulley that is attached to a structure; a fixed pulley does not give any mechanical advantage.

Force

A push or pull exerted on an object

Vector

A quantity that has both size (magnitude) and direction. Example: Velocity, Displacement, Weight, Force, Acceleration VFW-AD

Work

A result of a force moving an object a certain distance; The application of force over a distance

Circuit Breaker

A reusable safety switch that breaks the circuit when the current becomes too high

Lever

A rigid bar that is free to move around a fixed point

Common type of DC voltage (example)

AA, AAA, C, D batteries, as well as batteries for automobiles, smartphones, tablets and laptops

Current is measured in

Amperes (amps) (A); Measures the flow of charge in a circuit

Example of conservation of energy

An electric kettle will change electrical energy into heat energy. The energy is created (or destroyed) only changed

A hydraulic system transmits pressure using

An input system, and output system and fluid

Law of Inertia

Another name for Newton's First Law

Electrical load

Any device that purposely converts electrical energy to another form of energy in an electrical circuit. Examples include a lightbulb, a resistor and a motor. A load converts electricity into heat, light or motion

Applied Force

Any force applied to an object by another object

Bernoulli's Principle

As the speed of a horizontally flowing fluid increases, its pressure decreases.

Why are valence electrons the most reactive?

Because they are farthest from the nucleus and therefore the most reactive.

Buoyant Force pushes in what direction

Buoyant Force pushes vertically against the weight of an object

Electric Potential Difference

Called 'Voltage' (V); Measurement of the unit charge required to move between two points

What is the electromotive force in a battery?

Chemical processes

Mechanical advantage of a lever arm (B)

Effort Arm / Resistance arm

Direct Current (DC)

Electric current that flows in only one direction

Conservation of Energy

Energy cannot be created or destroyed, only transferred

Chemical Potential Energy (CPE)

Energy stored in chemical bonds Examples: batteries, natural gases, and coal

Newton's Third Law of Motion

For every action there is an equal and opposite reaction

For the torque equation to be valid, r and F must be

For the torque equation to be valid, r and F must be perpendicular to each other Maximum torque is produced when the force is perpendicular to the wrench

What force holds stars and planets together and keeps them in orbit?

Gravitational Force

What force keeps humans on the surface of the Earth?

Gravitational Force

Do insulators have high or low resistivity?

High (it opposes the flow of electricity)

Strong nuclear Force

Holds together the nucleus of an atom

Cycle of a four stroke engine

Intake, Compression, Power, Exhaust (Suck, squeeze, bang, blow)

Tension

Is found in ropes pulling or holding up an object; Stress that occurs when forces act to stretch an object

Circuit

Is made up of conducting wires that connect circuit elements, such as resistors, capacitors, and inductors; A path for an electrical current to flow around

SI unit for energy

Joule (J)

Mechanical advantage of an inclined plane 5

Light of scope / height (10/2)

Do conductors have high or low resistivity?

Low (doesn't oppose the flow of electricity well)

How to determine required effort of moving an object up a ramp If a ramp measures 6 feet in length and 3 feet in height, an object weighing 200 pounds requires how much effort to move using the ramp?

Make a proportion Length / = Weight / Height Effort

Difference between mass and weight

Mass is how much matter an object has (how much stuff there is) and weight is how strong gravity pulls on the matter of a mass.

Torque

Measurement of the force which causes something to rotate around a fixed point; The force required to rotate an object; A measurement of how much force you need to rotate an object

Moveable Pulley System

Mechanical advantage Dividing up the weight of this object If move down pulley one foot, it will move the weight only ½ foot. Apply 5 pounds of force to move ten pounds Every loop you make around the pulley that has the ten pounds cuts the weight in half

What is the electromotive force in a generator?

Mechanical processes

Watt's Law (Power [electrical] equation)

P = (Voltage)(Current) P = (V^2)/R

Nuetrons

Neutral particles that don't have an electric charge

The SI Unit for Force is the

Newton (N)

Force is measured in

Newtons

Magnitude of electrical force of charges is given in ....

Newtons (N)

What is the SI Unit for torque

Nm (Newton-meters)

Normal Force is always equal and opposite to ____

Normal Force is always equal and opposite to the force pushing onto the surface

Mechanical advantage of gears

Number of teeth on driven gear/ number of teeth on driving gear

Objects will have the highest moment of inertia when ....

Objects will have the highest moment of inertia (resistance to being rotated) when the mass is located at a larger distance from the axis of rotation than the other objects

Resistance is measured in

Ohms (Ω)

On Earth, gravity =

On Earth, gravity = 9.8 m/s^2

On a free-body diagram, which direction does friction point?

On a free-body diagram friction always points in the direction opposite the objects motion.

The distance between the threads of a screw is called what

Pitch Pitch, or thread pitch, is the distance between two adjacent thread crests, which should be a consistent distance between all threads on a fastener.

Gravitational Potential Energy

Potential energy that depends on the height of an object Examples: A book on a table before it falls, a child at the top of a slide, ripe fruit before it falls.

Are protons positive or negative?

Protons are positive (+)

OTHER SIDE The closer the string is to the center of the pulley, the faster the pulley rotates. Pulleys A and C are the same size, but the string is on the outer edge of Pulley A, so it will rotate slower than both C and B. (B) Correct.

Pulley A will rotate A. faster than both Pulley B and Pulley C. B. slower than both Pulley B and Pulley C. C. slower than Pulley B but with the same speed as Pulley C

OTHER SIDE When the ropes in the pulleys are crossed, adjacent pulleys rotate in opposite directions. Pulley B is in the middle, so it will be rotating in the opposite direction of the other two pulleys. (C) Correct.

Pulley B will rotate A. in the same direction as Pulley A but opposite of Pulley C. B. in the same direction as both Pulley A and Pulley C. C. in the opposite direction of both Pulley A and Pulley C

What does a ohmmeter measure?

Resistance (ohms)

What is sliding (kinetic) friction

Results when the surface of one object slides along the surface of another object

Mechanical advantage of wheel and axle equation

Rw / Ra radius of wheel/radius of axle

examples of first class levers

Scissors, pliers, seesaws, crowbar

Atom

Smallest particle of an element; Base unit of matter

What is the electromotive force in photovoltaic cells?

Solar power

Voltage sources

Sources of voltage

Equation for torque

T = rF t is torque, r is the radius and F is the force where r and F are perpendicular

The larger the radius of a pulley ...

The larger the radius of a pulley the slower it will turn

OTHER SIDE If Pulley B is the driver and turns clockwise, which pulley turns the slowest?

The larger the radius of a pulley, the slower it will turn. Because Pulley C has the largest radius, it will turn the slowest.

Newton's Law of Universal Gravitation

The law that says every object in the universe attracts every other object, and that the force is affected by mass and distance: the greater the mass of an object, the greater the attraction; the farther apart the objects, the weaker the attraction.

A third class lever will have a mechanical advantage of __

The load is further away from the pivot than the effort. There is no mechanical advantage because the effort is greater than the load

The longer and _____ the wire, the more resistance

The longer and thinner the wire, the more resistance

Will a longer or shorter lever have more torque?

The longer the lever the easier to rotate (the longer the wrench the easier to turn the bolt); the longer the wrench the more torque https://www.youtube.com/watch?v=8yMUn6RoHn4&ab_channel=JamesDann%2CPh.D.

What determines whether the mass moves up or down?

The magnitude of the two forces determines whether the mass moves up or down.

The mechanical advantage (MA) of a pulley system is equal to the number of ropes

The mechanical advantage (MA) of a pulley system is equal to the number of ropes supporting the moveable load Examples: https://www.teachengineering.org/lessons/view/cub_simple_lesson05

Is the nuclei of an atom positive or negative?

The nuclei of an atom is positive

What is contained in the nucleus of an atom?

The nucleus contains protons and nuetrons

Is the nucleus heavy or light?

The nucleus is heavy and may be considered rigid while electrons move freely

To balance objects of different weights you must make sure that _______ is equal

To balance objects of different weights you must make sure that their torques are equal by multiplying the radius (distance) from the force (ex: weight). https://www .youtube.com/watch?v=Cl1xVd71Sao&ab_channel=TheOrganicChemistryTutor

Ohm's Law

V = IR voltage = current x Resistance

What determines a materials conductivity?

Valence shells

Is force a scalar or a vector?

Vector because it has both size and a direction

What does a multimeter VOM measure?

Voltage, current, and resistance.

What is the equation for work

W = Fd F is force, d is the distance

Equation for power

W = work done (or energy converted) over an amount of time taken, t P = Work done / Time taken F is a force, v = speed

Weight =

W=mg W is weight, M is mass and G is gravity

SI unit for power

Watt (W)

Static Equilibrium

When an object has a net force of zero and is not moving

Dynamic Equilibrium

When an object has a net force of zero but is moving

Rotational Equilibrium

When an object is at rest or at a constant velocity (no acceleration - includes 'constant angular velocity') and it is NOT rotating OR is rotating at 'constant angular velocity' meaning that 'the angular acceleration is zero' (it is not accelerating)

When placed in an electric field, negative charges will ...

When placed in an electric field, negative charges will be pushed in the opposite direction of the electric field lines https://www.youtube.com/watch?v=laGSICm_agM&ab_channel=DerekOwens

When placed in an electric field, positive charges will ...

When placed in an electric field, positive charges will be pushed along the direction of the electric field lines https://www.youtube.com/watch?v=laGSICm_agM&ab_channel=DerekOwens

Is momentum conserved?

Yes, momentum is always conserved; meaning that the total momentum of a system remains constant.

Is it possible for the number of protons in an atom to change?

Yes, through nuclear reactions like in the sun or a nuclear weapon, but this is uncommon in daily experience.

Does water freeze at zero Celsius?

Yes. Water freezes at 0 C (32F) and boils at At sea level, water boils at 100° C (212F)

If a first-class lever with a resistance arm measuring 2 feet and an effort arm measuring 8 feet are being used, what's the mechanical advantage?

You can calculate mechanical advantage as Length of Effort Arm Length of Resistance Arm. Simply plug in the numbers: MA = 8/2 = 4

What is a capacitor?

a component that stores charge "holds a voltage across a gap between two conductive materials"

Free-Body Diagram

a diagram showing all the forces acting on an object

block and tackle pulley

a system of pulleys made of fixed and moveable pulleys; can have large mechanical advantages; is used to increase mechanical advantage

Valence shells that are close to full will more easily ...

accept electrons

Centrifugal Force

an apparent force that acts outward on a body moving around a center, arising from the body's inertia.

Impulse

change in momentum

Examples of second class levers

door, wheelbarrow, things w/ hinges, nutcrackers

Several gears in contact form what is called a ...

gear train

Four Fundamental Forces

gravitational, electromagnetic, strong nuclear, weak nuclear

A second class lever will have a mechanical advantage of __

greater than 1

Lack of electrons is also called

holes

Other Resources

https://www.airwarriors.com/community/threads/2nd-attempt-on-the-oar.48222/ https://www.mometrix.com/academy/oar-exam/

Practice Tests

https://www.crackasvab.com/asvab/mechanical-comprehension/test4.html

Momentum

mass x velocity Any object that has mass and is also moving has momentum. "mass in motion"

Density = The more volume an object has, the less ______ it is.

mass/volume The more volume an object has, the less dense it is.

Electrons move in circles around the

nucleus

When something is without charge (neither positive nor negative) it is called

nuetral

Mechanical Advantage of a pulley

number of pulleys used

Fluid friction

occurs when a solid object moves through a gas or liquid, like a fish in water or a bird flying through the air

Normal Force

occurs when an object is resting on another object

What does a hydraulic system do?

perform tasks through using a fluid that is pressurized; multiplies force

What does a voltmeter measure?

potential difference (voltage)

A higher electrical potential means a higher ...

potential energy

Common type of AC voltage (example)

power outlets

More mass means more inertia, meaning that more massive object has a greater tendency to

resist changes in its state of motion.

examples of insulators

rubber, plastic, wood, glass

Electrons orbit the nucleus in increasing energy levels called

shells

examples of semiconductors

silicon and germanium

Gear Ratio is also sometimes called ...

speed ratio

Four types of friction

static, sliding, rolling, fluid

Potential Energy (PE)

stored, potential energy that results from the position or shape of an object "Get ready energy"

What is the SI unit for work

the joule (J)

Second class lever

the load is between the fulcrum and the effort; The Effort is on the outside opposite the fulcrum

In a free-body diagram, the vector for tension always points along the rope away from

the object

Power

the rate at which work is done (how quickly you can move something over a distance)

moment of inertia

the resistance to being rotated

Electromagnetic Force is repulsive when charges are

the same sign (positive-positive or negative-negative)

What wire will have less resistance, a wire that is long and thin or a wire that is short and fat?

the short and fat chord

Electric Field

the space around a charged object in which another charged object experiences an electric force https://www.youtube.com/watch?v=VFbyDCG_j18&ab_channel=ProfessorDaveExplains

Atoms with a full valence shell are

unreactive