Physics Flashcards
Precision
How close the measured values are to similar value
Accurate
How close a measured value is to the real value
Random error
Results where the last digit is estimated, can be reduced by taking several measurements.
Systemic error
Due to a problem with measuring devices, reduced by adding or subtracting the error or calibrating the device.
Motion
Involves a change in position of an object over time.
Kinematics
The study of motion
Uniform motion
mouvement at a fixed speed in a set direction(straight line).
Non-uniform motion
mouvement that involves changes in speed and direction or both
Vectors
A line segment that represents motion from start to finish
Scalar quantities
only have magnitude(size)
Vector quantities
have both magnitude and direction
Position
Distance and direction of an object from a reference point, vector quantity
Displacement
The change in an object’s position, vector quantiy
Speed
Distance travelled per unit time, scalar quantity
Velocity
Displacement of an object per unit time, vector quantity.
Acceleration
Rate of change of velocity per unit time
Position time graph
Describes the position of an object over time, straight line represents constant velocity, slope represents velocity
velocity-time graph
Describes the velocity of an object over time, slope of the graph represents acceleration of the object, steeper the slope the greater the accleration, area under a velocity time graph gives the displacement
Acceleration-time graph
Describes the acceleration of an object over time, area under graph gives the change in velocity
Forces
A push or pull acting on an object
Applied force
Force applied to an object by a person or another object
Gravity Force
directed downwards towards the centre pf earth
Normal force
The force perpendicular to the surface of contact
Friction force
The force exerted by a surface as an object slides across it
Tension force
The force transmitted through a string
Spring Force
The force exerted by a streeched or compressed spring.
Gravitational force
Weak force, longest range
Electromagnetic force
Caused by electric charges, attraction or repulsion, holds atom and molecules together, strong force and long range
Strong nuclear force
between particules in the nucleus of an atom, strongest force, short range
Weak nuclear force
holds elementary particles together, responsible for radioactive decay, strong force, short range
newton’s 2 law of motion
If the net external force of an object is not zero, the object will accelerate
newtons’s 3 law of motion
For every action force there is a reaction force equal in magnitude but opposite in direction. the action-reaction law
Newton’s 1 law
law of inertia: property of matter that causes it to resist changes in motion, more mass=more inertia. If the net external force on an object is zero, the object will remain at rest or continue to move at constant velocity.
Friction
Resists motion and acts in a direction opposite to the direction of motion
Static friction
Force that prevents a stationary object from starting to move. AMount of force an object must overcome in order to start moving
Kinetic friction
Force that acts against an object that is in motion, acts in the oppsite direction of mouvement.
Mass
Quantity of matter in an object, constant
Weight
Measure of the force of gravity acting on the object
Mechanical work
When a force displaces the object in the same direction of the force
work
directly proportional to both applied force and displacement
positive work
Force and displacement are in the same direction, speed increases, adds energy to system
negative work
removes energy from the system, force and displacement are in opposite directions, speed of the object decreases.
kinetic energy
energy possessed by a moving object, faster and object moves=greater kinetic energy
energy
the ability to do work, scalar quantity
Potential energy
A stored form of energy, ability of an object to do work, greater the height of the object=greater potential energy
the sum of kinetic and potential energy=
mechanical energy
energy transformation
The conversion of energy from one form to another
law of conservation of energy
the total amount of energy in the universe is conserved, energy is neither creater nor destroyed, it is changed from form to form, none is lost
Efficiency
a ratio, useful energy provided by the device to the energy required to operate the device
Power
The rate at which energy is transformed or the rate at which work is done, scalar, in watts
Waves
Disturbances that transfer energy over a distance
Vibration
Cyclical motion about an equilibrium point
