Acceleration is the rate of change in velocity or the change in velocity divided by the change in time.Acceleration can be expressed as:
a = dv/dt = d2x/dt
2,
Where, v = velocity, t = time, x = position, d = change-in
In SI units acceleration is expressed as meter per second squared, or m/s
2. Acceleration due to the earth's gravity at the earth's surface is 9.81 meters/sec
2 and is commonly referred to as g. Cornering a car at 1g means that the centrifugal acceleration and the gravitational acceleration is equal.
Accuracy is the maximum error in the measurement of a physical quantity. A measurement may have accuracy without precision by having widely dispersed reading which average very close to the true value.
Acoustics, or acoustical, pertains to sound or the science of sound.
Adiabatic changes occur in a system or substance without a change in the actual heat energy content. For example; adiabatic cooling may occur in a closed air system by reduction of pressure without losing energy.
Aerodynamics is the science of motion of air or other gases and their interaction with other objects. Aerodynamic drag is the force the resists a cars movement through the air.
Alkaline cell, also called alkaline-manganese cell, is a primary cell similar to the zinc-carbon cell, but has 50 to 100 percent more capacity. This cell uses a potassium-hydroxide electrolyte.
Alternating Current is electrical current in which the charge flow periodically reverses and whose average value is zero.
Alternator is a device for converting mechanical energy into alternating current electrical energy.
Ammeter is an instrument for measuring current and may be scaled in microamperes, milliamperes, amperes, or kiloamperes.
Ampere or Amp is a unit of measure of electric current. One amp will flow through one ohm of resistance when one volt is applied. An amp is equal to one coulomb (6.25 * 10
18 electrons) of charge passing a point in one second.
Ampere's Law for the force in a conductor states that any conductor carrying a current and located in a magnetic field will be pushed by a force that is proportional to the flux density, to the current and to the length of wire.
Amp-hour is the amount of energy in one amp of current flowing for one hour. This is the unit of measure for the energy held in a battery. The amp-hour capacity is determined by the multiplying the current by the time the current flows to drain a battery. (This capacity actually varies depending on the rate of discharge)
Amp-Hour Meter is used to measure the amount of electric current used or consumed by a circuit.
Amp-turns is the magnetomotive force produced by a coil, derived by multiplying the number of turns of the conductor in the coil by the current through the coil.
Anion is a negatively charged ion that moves toward the anode during electrolysis or in a CRT, cell or similar device.
Anode is the positive, or less noble, electrode of an electrolytic cell.
Anodizing is the electrochemical oxidation process.
Armature is the moving portion of an electromechanical device.
Battery is a dc voltage device which converts chemical, thermal, or solar energy into electrical energy.
Battery Acid is the solution that serves as the electrolyte in a storage battery. In lead-acid batteries the electrolyte is diluted sulfuric acid.
Centrifugal Force is the force acting on a rotating body or a cornering vehicle acts from the body toward the center of rotation.
F
c = mass * velocity
2 / radius of arc
This is the force acting on the tires of an automobile as it corners. (The centrifugal force acts perpendicular to the direction of travel - only the slip angle of the tires can contribute to the work of cornering).
ChargeThe basic unit of charge is the Coulomb and is equal to 6.25 * 10
18 electrons' charge. Electrons carry a negative charge and protons carry positive charges.
Conservation of Energy states that a) energy is never created or destroyed; b) in transforming energy from one form to another, energy is always conserved; and c) the total sum of energy in this Universe remain constant.
Conservation of Momentum states that when two or more bodies combine or separate the total momentum does not change unless acted upon by outside forces. Momentum is equal to mass * velocity
2 / 2 and is a constant for a system even if the parts are moving in different directions.
Curb Weight is the total weight of the vehicle including batteries, but excluding the operator, passengers and other payload.
Current is the movement of charged particles. In a wire this is commonly referred to by the movement of electrons. One Ampere of current is movement of one coulomb (6.25 * 10
18 electrons) past a point in one second.
Density is the mass per unit volume.
In SI units, kg per liter (kg/l) or grams per milliliter may be used. In silly units, stones per cubic angstrom may be used.
Diamagnetic material acquires a magnetization opposite to the external field.
Drive-Line Ratio is the motor output shaft RPM divided by the RPM of the traction wheels of the vehicle.
Dynamic Index is the square of the radius of gyration (k) of the sprung mass of a vehicle about a transverse axis through the center of mass, divided by the product of the two longitudinal distances (a and b) from the front and rear wheel centers.
Dynamic Index = k
2 /a * b
Electric Field is the region about a charged particle and is proportional to the charge of the particle divided by the dielectric constant for the intervening material and the square of the distance.
Energy is an "amount" and comes in many forms. Potential energy can be chemical, like in a battery, or mechanical, like water pressure behind a dam. Kinetic energy is in a mass moving, like a car on the highway. Energy is never created or destroyed, but is always being converted from one form to another. The potential energy of water pressure behind a dam is converted to electrical energy at the generators and goes through the wires to charge the batteries (chemical energy) in the electric car. The potential energy in the batteries is converted to mechanical kinetic energy at the motor to drive the car and when the car is stopped the kinetic energy is converted heat energy in the brake drums.
Work, torque and heat are all forms of energy.
In SI units energy is in watt-seconds or joules.Watt-hours, Newton-meters and calories are commonly used. Generically, energy is power times time.
Faraday's Principle states that when a magnetic field cuts a conductor, or when a conductor cuts a magnetic field, an electric current will flow through the conductor if a closed path is provided by which the current can circulate.
Ferromagnets retain a substantial magnetization after the external magnetic field is removed. Magnetization in this material depends on the total magnetization history of the material.
Force is the time rate of change of momentum or mass times acceleration. Commonly, a force can be thought of as a push or pull on an object. The force of gravity, known as weight, is equal to the mass of the object times the acceleration of gravity (g). A 1000 kilogram (kg) cars weighs 9810 newtons (N). For conversions to English units, 1 kilogram mass weighs 2.205 pounds.
Force = mass * acceleration [kg-m/s
2]
A 1000 kg car will exert a force of 5000 N on the pavement to accelerate at 5 meters/second2. Force = power/velocity = work/distance
Gradeability is the maximum percent grade which the vehicle can traverse for a specific time at a specific speed. The gradeability limit is the grade on which the vehicle can just move.
Heat is a quantity of thermal energy. A body may contain heat and heat may move from body to body. Heat, being energy, is never created or destroyed, but only converted from, or to, other forms of energy, concentrated or dissipated. When the friction brakes of an automobile are applied, the kinetic energy stored in the moving mass of the vehicle is converted to heat energy in the brake drums and rotors.
Horsepower, in the old English units, was the unit of power and was equal to 33,000 foot-pounds per minute or 550 foot-pounds per second. One horsepower is equal to 0.746 kilowatts.
Impedance, in electric circuits, is the total opposition to current flow caused by either the material or the electromagnetic field through which the current is flowing. Impedance is measured in ohms and uses the symbol Z. In a D.C. circuit, impedance is the same as resistance.
Inertia is the property of matter that causes it to resist any change in it's motion or state of rest.
Initial State of Charge is the amount of energy stored in the battery. This can be expressed as a percentage of the capacity obtainable from a fully charged battery when discharged at a rate equivalent to the vehicle maximum cruise speed discharge rate.
Joule is the unit of work, energy or heat in the SI system. One joule is the work done when the force of one newton is applied over a distance of one meter.
Kinetic Energy is the ability of a moving mass to do work by virtue of its motion. The amount of energy is 1/2 * mass * velocity
2 .
Lenz's Law states that whenever a current is set up by a flux through a circuit, its direction will be such as to oppose the act which caused it.
Mass is the quantity of matter in an object, or more correctly, the measure of inertia of a body. An object's mass can be determined by dividing its weight by the acceleration of gravity.
Magnetic Fields are due to either an electric current or a magnet. In the case of magnetic fields due to a current the field intensity H is proportional to the current flowing through the conductor and inversely proportional to the distance from the conductor. For the case of a magnetic field due to a magnet, the field intensity is proportional to the magnetic strength of the poles and inversely proportional to the distance from the magnet.
Moment of Inertia is derived by multiplying the elementary particles of mass by the square of their distances from a reference axes. In most cases the actual value or formula for a particular shape is found in a table. As an example, the formula for a rectangle with the axes passing through the middle of the smallest surface is:
Jm = M * (a
2+b
2)/12
Newton's First Law states that a body will remain at rest or in uniform motion in a straight line unless acted upon by a force to change its state of rest or motion.
Newton's Second Law states that a change in motion for a body is directly proportional to the applied force and in a direction collinear to the applied force.
Newton's Third Law states that for every action there is an equal reaction in the opposite direction.
Ohm's Law states that the current in a conductor is equal to the voltage across that conductor divided by the resistance of the conductor.
Paramagnetic is the property of a material to acquire magnetization parallel to a magnetic field.
Permeability is the ability for a material to be magnetized under the stimulation of a magnetic field. High permeability means easily magnetized.
Potential Energy is the ability of a body to do work by virtue of its position or state. These include a) its gravitational state(mgh); b) its thermal state; c) its chemical state (batteries); d) its electrostatic state or; e) its mechanical state (springs).
Power might be easily thought of as the rate of energy conversion or the rate of work being done. As an electric car accelerates the energy in the batteries is converted to the kinetic energy of the car at a certain rate or power.
Watts, kilowatts or joules per second are the SI units of measure for power. Generically, power is the product of force times distance divided by time.
Power = force * velocity = work / time.
Power Factor is the ratio of the actual power of an alternating or pulsating current, as measured by a wattmeter, to the apparent power as measure by a voltmeter and ammeter. In other words, power factor is an indication of the phase difference of the current's sine wave to the voltage's sine wave. A power factor of one indicates voltage and current are in phase. Many battery chargers have power factors of 0.7 or less.
Projected Frontal Area is the total area of the vehicle obtained by projecting its image on a vertical plane normal to the vehicles direction of travel.
Radius of Gyration with reference to an axis, is that distance from the axis at which the entire mass of a body may be considered as concentrated, with the moment of inertia remaining unchanged.
The formula for the radius of gyration is: k = square-root(Jm/M)
where k is the radius of gyration in meters, Jm is the polar moment of inertia in kilogram * meter squared, and M is the mass of the object in kilograms.
Resistance is the property of a material which impedes current flow. Material, temperature and size of the conductor all affect the resistance. Resistance is given in ohms. One ohm will cause a one volt drop when one amp is flowing.
Resistance = Voltage / Current; R = E / I
Shunt is a known low resistance conductor placed in parallel with a meter in order to reduce the current through the meter. This is used to measure large currents that would normally destroy a meter is applied directly.
Specific Heat is the amount of energy required to raise an amount of material in temperature.
In SI units it is stated as kilojoule per kilogram per degree C.
kJ/kg/°C = J/g/°C
Spring Rate is the change in load per unit amount of deflection of the spring. May be stated as Newtons per meter.
Sprung Weight is the weight which is supported by the suspension, including a portion of the suspension members.
Sprung Mass is the mass of the sprung weight.
Thermal Coefficient of Resistance is multiplied by the temperature and added to the base-line resistance of a conductor. The coefficient is usually a positive number.
Thermal Conductivity is the rate of heat energy transfer through a given material due to a temperature difference or gradient.
In SI units its watts per meter per degree C.
W/(m-°C)
Torque or moment of a force is a measure of the tendency of force acting on a body to rotate that body. Only the component of the force which is perpendicular to the axis of rotation and in a plane perpendicular to the axis of rotation adds to the torque.
In SI units, torque is recorded in newton-meters (the same as energy).
Tire Rolling Radius is the effective radius of the tire supporting the actual vehicle weight as the vehicle travels.
Tractive Force is the force available from the drive wheels at the road surface.
Velocity at a point in time is equal to the acceleration times time plus the initial velocity.
v
t = v
0 + a * t [meters/second].
Velocity in the lab is generally stated in meters per second and on the road as kilometers per hour, kph.
Voltage or Potential or electromotive force (EMF) are all names for the force exerted on electrons to cause a current to flow through a resistance.
Voltage = Current * Resistance; E = I * R
Large voltages of several thousand volts can be developed in the static charges on a person or their house cat. Because the resistance is in the millions of ohms, no current will flow. That is until you either touch or get very close to the cat or a door knob or such. This is referred to as a static charge because it is not moving.
Weight is the Force of gravity. Weight is equal to the mass time the acceleration of gravity.
Weight = mass * gravity-force; W = m * g
In SI units weight is in Newtons (N), mass is in Kilograms (kg) and g is in meters/sec
2. In the old English system things are sold by weight and in metric countries things are sold by mass. Mass is always the same no matter where it is measured - weight is dependent upon the location (with respect to the mass of the Earth) of the measuring device.
Wheel Caster Angle is the angle, in side elevation, between the steering axis and the vertical. It is considered positive when the steering axis is inclined rearward (in the upward direction) and negative when the steering axis is inclined forward.
Wheel Chamber Angle is the inclination of the wheel plane to the vertical. It is considered positive when the wheel leans outward at the top and negative when the wheel leans inward.
Wheel Toe is the angle between the plane of the wheels and the longitudinal axis of the vehicle. The Toe angle is considered toed-in if the forward portion of the wheel is turned toward the central vehicle axis and toed-out if the forward portion of the wheel is turned away from the central vehicle axis.
Work, or energy, is equal to force times distance. Only the force that is in the direction of the distance traveled counts toward the work. Swinging a mass on a string produces no work since the centrifugal force along the string is perpendicular to the direction of travel of the mass. Pushing a vehicle produces work.
The drag forces (air, rolling, mechanical friction) times the distance over which the vehicle is pushed is equal to the work.
In SI units work is in Newton-meters (N-m) or joules (J).
The work to stop a moving vehicle is mass * velocity
2 / 2.
Work = force * distance = power * time
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