2.2 Mechanics Flashcards by orkanor Unknown

What is newtons first law

Body will remain at rest or continue to move unless acted upon by a force

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What is force

vector quantity
has magnitude and direction

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What is moment

Turning effect produced by a force acting at a distance

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What is opposing moments

Total moments that act against each other and are applied at points separated by a distance

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What is a couple

Pair of forces that are equal in magnitude and opposite in direction

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What is scalar quantities

Have magnitude but no direction

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What is vector quantities

Have both magnitude and direction

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What is Centre Of Gravity

Imaginary point where all weight of object is said to act

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Five basic structural stresses

Tension
Compression
Shear
Bending
Torsion

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What is strain

Deformation of material due to stress

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What is elasticity

Ability of material to return to its original shape after external force has been removed

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What is tension

Stress being applied which tends to increase the length of body

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What is hooke’s law

Extension of an elastic object is directly proportional to the force applied to it

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Young’s Modulus

Stress/Strain

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What is compression

Force applied which tends to shorten or squeeze a body

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What is shear

Tries to slice a bod apart by sliding one later over another

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What is torsion

When material is twisted
Combination of tension and compression

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What is hardness

Tendency to resist indentation

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What is strength

Withstand applied force without failure

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What is toughness

Tendency to resist breakage when deforming or when impact forces are applied

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What is brittleness

Tendency to break without change of shape

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What is elasticity

Return to original shape when external force is removed

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What is Malleability

Tendency to undergo compressive stress without damage

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What is ductility

Tendency to undergo tensile stress without damage

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What is inert

Substance that will not chemically combine with another substance

What is atmospheric pressure

Force exerted by weight of the atmosphere

Average atmospheric pressure at sea level

14.7 PSI

What is absolute pressure

Pressure of having nothing inside a space (perfect vacuum)

What is motion

Continuing change of position

What is velocity

Change in displacement over time

What is acceleration

Change in velocity over time

When is acceleration constant

When acceleration is caused by earths gravitational attraction

Atmoic number of certain elements

aluminium 13 copper 29 titanium 22 oxygen 8 nitrogen 7 carbon 6

What is centrifugal force

Force pushing away from the centre of the curve

What is centripetal force

Force accelerating towards the centre of rotation (pulling inwards)

What is damping

Decrease of vibrations as a result of removing energy through resistance of motion

What is pendular movement

Movement the pendulum will undergo if it is given a small displacement from its vertical position

What is vibration

Mechanical oscillations about an equilibrium point

What is free vibration

Set off with initial input and allowed to vibrate freely (Pulling child back on swing)

What is forced vibration

Occurs when a continuous force or motion is applied to a mechanical system

What is velocity ratio

How far the effort has to move in relation to the load

What is mechanical advantage

Ratio of the force produced by the machine to the force applied

What is actual mechanical advantage

Ratio of the output and input force

What is ideal mechanical advantage

Would exist if there is no friction

What is a lever

Rigid bar capable of turning about a fixed axis called fulcrum

What is a first class lever

Fulcrum located between effort and resistance example crowbar

What is a second class lever

Fulcrum at one end effort applied to opposite end example wheelbarrow

What is a third class lever

Effort applied is located between the fulcrum and the resistance example landing gear

What is a spur gear

Straight cut teeth through circumference and are used to connect two parallel shafts

What is a bevel gear

Transmit power between two shafts at an angle for each other

Pascals

Hectopascals

when is worm gear used

Used when a large reduction in speed is needed and for correspondingly high torque multiplication

SUVAT

S= Displacement m U= Initial Velocity m/s V= Final velocity m/s A= Acceleration m/s2 T= Time s

What is sun and planet gears

Large amount of speed reduction and torque needed

What is mass

Amount of matter in a body regardless of its volume or position

What is weight

Gravitational force of attraction between mass of earth and mass of body

What is work

Force causing movement

What is power

Measure of the rate at which work is done

What is potential energy

Energy a body has due to its position

What is kinetic energy

Energy body has due to its motion

What is momentum

Vector quantity that describes mass in motion

What is a gyroscope

spinning mass which possesses the properties of rigidity and precession

What is friction

Friction is the force resisting the relative motion of materials rubbing against each other

What friction is greatest

Starting friction

What friction is smallest

Rolling friction

How do you convert kg/m3 to g/cm3

Divide by 1000

How do you convert g/cm3 to kg/cm3

Multiply by 1000

What is viscosity

Resistance of a fluid to a change in shape

What is static pressure

Exists in addition to any dynamic factors that may also be present at the same time

What is dynamic pressure

Pressure that emerges from velocity to the fluid in motion