Module 3 all Flashcards
Displacement
the shortest distance between any two points
Velocity
The rate of change of displacement with respect to time; it has both magnitude and direction.
Acceleration
The rate of change of velocity with respect to time.
Force
A push or pull on an object, causing it to accelerate.
work done
the product of the magnitude of the force and the distance moved by the object in the direction of the force
power
the rate of transfer of energy
momentum
the product of an objects mass and velocity
conservation of energy
in a closed system, energy cannot be created or destroyed, but only transferred from one form to another.
factors affecting air resistance
- velocity
- density of air
- surface area of shape
weight
the gravitational force acting on an object in newtons (N)
newton
A force of 1 Newton applied to a 1 kg mass will give it an acceleration of 1 ms-2
difference between centre of mass and gravity
centre of mass is point through which externally applied force produces straight line motion but no rotation, while gravity is the point at which entire weight of object appears to act
tension
pulling force exerted by string, cable or chain
drag
the resistive force exerted by fluid on object moving through it
principle of moments
for a body in rotational equilibrium, sum of the anticlockwise moments about any point equal to sum of clockwise moments about same point
moment
turning effect of force about axis or point, moment = force x perpendicular distance of line of action from axis
torque
the product of one of the forces of couple and perpendicular distance between forces
couple
a pair of equal and opposite forces acting on a body but not in same straight line
density
the mass per unit volume of substance
pressure
the force exerted per unit cross sectional area measured in pascals
upthrust
the upward buoyant force exerted on a body immersed in a fluid
archimedes principle
the upthrust on an object in fluid is equal to the weight of fluid displaced
principle of conservation
total energy of a closed system remains the same before and after a collision
gravitational potential energy
the capacity for doing work as a result of an objects position in gravitational field
Kinetic energy
the energy associated with an object as a result of its motion
energy
the capacity to do work, measured in joules (J)
hookes law
The force applied is directly proportional to the extension of the spring unless limit of proportionality is exceeded
tensile and compressive derformation
a change in shape of object due to tensile force/compressive force
elastic limit
the value of stress or force beyond which elsatic deformation becomes plastic deformation, material no longer return to original shape when stress/force removed
elastic and plastic deformation
elastic is reversible change in shape of object due to compressive or tensile force with removal of stress returning to original shape and size. Plastic is irreversible change with permenant deformation when force removed
force constant
a quantity determined by dividing force by extension for object obeying hookes law, measures stiffness of spring, measured in Nm^-1
parallel and series spring rule
k=k1+k2 for parallel
k = 1/k1 + 1/k2 for series
loading and unloading
tensile stress
the force per unit cross sectional area, measured Pa
tensile strain
the extension per unit length, a ratio of extension to original length
limit of proportionality
the value of stress beyond which stress no longer is directly proportional to strain
yield point
a point on stress-strain graph beyond which deformation no longer elastic
ultimate tensile strength
the max stress material can withstand before break
young modulus
ratio of tensile stress to strain when quantities directly proportional to eachother, measured Pa
newton first law
object will remain at rest or constant velocity unless acted upon by resultant force
newton second law
resultant force acting on object is directly proportional to rate of change of momentum and in same direction
newton third law
when two objects interact, they exert equal and opposite forces on eachother
conservation of momentum
for system of interacting objects, total momentum in specific direction is constant, as long as no external forces act on system
perfectly elastic collision
collision in which no kinetic energy lost
inelastic collision
collision in which kinetic energy lost
impulse
the area under force-time graph, the change in momentum
Archimedes’ Principle
The upwards force acting on an object submerged in a
fluid, is equal to the weight of the fluid it displaces
Couple
Two equal and opposite parallel forces that act on an object through
different lines of action. It has the effect of causing a rotation without translation.
Newton’s Second Law
The sum of the forces acting on an object is equal to the
rate of change of momentum of the object.
Tension
The result of two forces acting on an object in opposite, outwards
directions
Newton’s Third Law
Every action has an equal and opposite reaction. If an
object exerts a force on another object, then the other object must exert a force
back, that is opposite in direction and equal in magnitude
