M2.2 Flashcards
What does an atomic number denote
Number of protons
What does atomic mass consist off
Protons and neutrons
What is fluid resistance
It occurs when a solid object travels through a liquid or gas, or when a liquid travels through a solid. This causes resistance to motion within the fluid
What is viscosity
It’s the measure of a fluids resistance to flow
What happens to a liquids viscosity if temperature increases
The viscosity of a liquid decreases rapidly with an increase in temperature. Whereas a gas increases with an increase in temperature
What is a vibration
Refers to the mechanical oscillations about an equilibrium point
What is a desirable vibration compared to an undesirable vibration
Necessary for correct functioning of various devices like a loud speaker. But undesirable as it could be an imbalance like an unbalanced wheel
What is free vibration
When a mechanical swing is set off with an initial input and then allowed to vibrate freely at its natural vibration unless it damps down.
Forced vibration
When a continuous vibration or motion is applied to a mechanical system. The frequency of the vibration depends on the force applied. Whereas the amplitude (height) of mechanical system
What is a harmonic
Harmonics are periodic frequency’s. Repeats itself at standard intervals. Can be described as sinusodual with constant amplitude.
Does a harmonic wave have a positive frequency
Yes. Harmonics have a positive integer followed by fundamental frequency’s - the lowest frequency in the periodic wave.
What is a fundamental frequency
One wave that doesn’t change its integer. The first harmonic of a harmonic series.
What is the equation for a wavelength of an harmonic
Wavelength = 2 divided n (index of harmonics) x length of the body
What is resonance
The tendency of a system to oscillate at a maximum amplitude when applied force equal or at its natural frequency.
What is velocity ratio
It’s how far the effort (force push or lift) has to move in relation to the load.
If the object has a velocity ratio greater than 1 then the distance moved by the effort is greater than the distance moved by the load.
What is the equation for velocity ratio
Velocity ratio = sin (distance in) divided sin sout (distance out)
What is mechanical advantage
The ratio of the force produced by a machine to the force applied to it. Used to access performance.
What’s the equation for MA
MA = resistance(N) divided Effort (N)
What is actual mechanical advantages (AMA)
The ratio of output over input. shows how much easier work can be done.
AMA = F out divided F in
What is ideal mechanical advantages (IMA)
Shows what would exist if there was no friction on machine.
IMA = sIn divided sOut (s being distance)
What is a first class lever
The fulcrum is located between the effort and the resistance (load). FLE. middle.
Increasing distance from effort to the resistance (load) increases advantage provided by lever. When effort is applied it acts in the opposite direction to resistance. Oppositing moment either side of fulcrum.
E x L = R x L
What is a second
Fulcrum is at one end of lever and effort is applied at opposite end - wheelbarrow. The mechanical advantage is the same with 1st and 2nd lever. Only difference is the resistance and effort on first class lever act in same direction.
Third class lever
Always at the end with effort in the middle and load at the end. Landing gear attaches to aircraft which acts as a piviot point.
Inclined planes
A plane surface inclined to a horizontal plane at any angle but a right angle. Advantage as it allows large resistance to be moved yet small effort.
F1 x S1 = F2 x S2
What is a pulley
A wheel which rope or chain is pulled in order to lift or lower a heavy object.
What is the mechanical advantage of a single pulley
1
What is the effort required to raise an object
Weight of object
What is a gear
Multiple single gears working together to alter the relation between speed and direction of a mechanism.
What is a drive gear
The one that drives the driven gear to produce angular velocity and torque.
What happens when drive and driven gear have have same amount of teeth
No mechanical advantage MA = 1
How do you find mechanical advantage
MA = Fout divided Fin. load divided by effort. Driven gear divided by drive gear
What is Newton’s first law?
States that a body will remain at rest or continue to move with a uniform velocity unless acted upon a force
What is force?
It is a vector quantity, so it has both magnitude and direction
Which gear turns quicker
The smaller gear
What is a moment?
A moment is a turning effect produced by a force acting at a distance with respect to an objects fulcrum, causing a body to rotate about a point
To work out the revolution ratio do you swap them around to what it would be for a gear ratio
Yes for a gear ratio it would be 2:1 but for revolution it would be 1:2
What are opposing moments?
They are total moments that act against each other against each other and are applied at points separated by distance
What is the equation for opposing moments?
M1=F1 x S1
What is a spur gear
Has their teeth cut straight across and are used to connect two parallel shafts. When both gears have external teeth shafts turn in opposite directions. Whereas if both need to go in same direction one must have internal teeth.
What is a couple?
A pair of forces that are equal in magnitude and opposite in direction, the combined moment of the forces produces a torque on the object they act on
What is stress?
it is the quantity that describes the magnitude of forces that cause deformation. Deformation is also known as strain.
What is stress always accompanied with
Strain
What is a bevel gear
Teeth cut into a convivial surface. Two gears mesh together to transit power between two shafts at an angle to each other. If gears are not parallel then a bevel gear is used.
What is elasticity?
The ability of a material to return to original shape once external forces have been removed
What is a worm gear
Has a toothed wheel worked by a short revolving cylinder called a worm. A screw thread. The worm is the driving component. Used for large reduction in speed. Hoisting machines
What is hookes law
Force equals spring constant times extension F=K x e
What is shear strength
Tries to slice a body by sliding one layer away from another