SPH3U1 - key definitions

the study of motion

a change in an object’s location as measured by a particular observer

the total length of the path travelled by an object in motion

the line an object moves along from a particular starting point

a quantity that has only magnitude (size)

a quantity that has magnitude (size) and direction

the distance and direction of an object from a reference point

the change in position of an object

a vector diagram drawn using a specific scale

a straight line between two points with a specific direction

the total distance travelled divided by the total time taken to travel that distance

the total displacement, or change in position, divided by the total time for that displacement

a graph describing the motion of an object, with position on the vertical axis and time on the horizontal axis

a measure of the steepness of a line

vertical change between two points on a line

horizontal change between two points on a line

motion of an object at a constant speed in a straight line

motion in which the object’s speed changes or the object does not travel in a straight line

how quickly an object’s velocity changes over time (rate of change of velocity)

a graph describing the motion of an object, with velocity on the vertical axis and time on the horizontal axis

motion in which velocity changes at a constant rate

the velocity of an object at a specifi c instant in time

a graph describing motion of an object, with acceleration on the vertical axis and time on the horizontal axi

the acceleration that occurs when an object is allowed to fall freely; close to Earth’s surface, g has a value of 9.8 m/s2

the acceleration due to gravity of an object in the absence of air resistance

the velocity of an object when the force due to air resistance equals the force due to gravity on the object

r a vector that results from adding two or more given vectors

vectors which when added together give the original vector from which they were derived; one component is parallel to the x-axis and the other is parallel to the y-axis

an object that moves along a two-dimensional curved trajectory in response to gravity

the motion of a projectile under gravity

the time taken for a projectile to complete its motion

the horizontal distance travelled by a projectile

the study of the causes of motion

he SI unit of force (1 N = 1 kg·m/s2)

a simple sketch of all objects involved in a situation

a simple drawing of an object showing all the forces that are acting on it

a force that results when one object makes contact with another and pushes or pulls on it

a pulling force from a rope or string on an object that always points toward the rope or string

) a perpendicular force exerted by a surface on an object in contact with the surface; the normal force always points away from the surface

opposes the sliding of two surfaces across one another; friction acts opposite to the motion or attempted motion

force of attraction between any two objects

the sum of all forces acting on an object

a the property of matter that causes it to resist changes in motion; inertia is directly proportional to the mass of the object

an object will remain at rest or continue to move at constant velocity when the net force on the object is zero

an object will accelerate in the direction of the net force; the magnitude of the acceleration is directly proportional to the magnitude of the net force and inversely proportional to the object’s mass

each action force has a reaction force that is equal in magnitude and opposite in direction

the motion of a falling object where the only force acting on the object is gravity

the maximum constant speed of a falling object

d a region of space surrounding an object that can exert a force on other objects that are placed within that region and are able to interact with that force

the force per unit mass acting on an object when placed in a gravitational field

a force of friction that prevents the sliding of two surfaces relative to one another

the force exerted on a moving object by a surface opposite to the direction of motion of the object

the ratio of the force of friction to the normal force

the ratio of the maximum force of static friction to the normal force

the ratio of kinetic friction to the normal force

applying a force on an object that displaces the object in the direction of the force or a component of the force

the capacity to do work

energy possessed by moving objects

the net amount of mechanical work done on an object equals the object’s change in kinetic energy

a form of energy an object possesses because of its position in relation to forces in its environment

energy possessed by an object due to its position relative to the surface of Earth

a designated level to which objects may fall; considered to have a gravitational potential energy value of 0 J

the sum of kinetic energy and gravitational potential energy

the total quantity of kinetic and potential energy possessed by the atoms or molecules of a substance

potential energy of protons and neutrons in atomic nuclei

the change of one type of energy into another

energy is neither created nor destroyed; when energy is transformed from one form into another, no energy is lost

the amount of useful energy produced in an energy transformation expressed as a percentage of the total amount of energy used

energy-rich substance

a substance that cannot be replenished as it is used in energy-transforming processes

a substance with an unlimited supply or a supply that can be replenished as the substance is used in energy-transforming processes

fuel produced by the decayed and compressed remains of plants that lived hundreds of millions of years ago

the decomposition of large, unstable nuclei into smaller, more stable nuclei

a nuclear reaction in which the nuclei of two atoms fuse together to form a larger nucleus

radiant energy from the Sun

building design that uses the Sun’s radiant energy directly for heating

a device that transforms radiant energy into electrical energy

electricity produced by transforming the kinetic energy of rushing water into electrical energy

the rate of transforming energy or doing work

reduced supply of electricity caused by system damage or excess demand

a large electricity distribution system composed of a network of electrical power plants and electricity distribution towers and cables

a positively charged particle in the nucleus of an atom

an uncharged particle in the nucleus of an atom

particles in the nucleus of an atom; protons and neutrons

a negatively charged particle found in the space surrounding the nucleus of an atom

state in which all electrons are at their lowest possible energy levels

e state in which one or more electrons are at higher energy levels than in the ground state

the number of protons in the nucleus

the number of protons and neutrons in the nucleus

a form of an element that has the same atomic number, but a different mass number than all other forms of that element

an unstable isotope that spontaneously changes its nuclear structure and releases energy in the form of radiation

energy released when the nucleus of an unstable isotope undergoes a change in structure

a process by which the nucleus of an atom spontaneously disintegrates

n the decomposition of large, unstable nuclei into smaller, more stable nuclei

the process by which the nucleus of an atom sometimes changes

the force of attraction or repulsion due to electric charges

the very strong force of attraction between nucleons

the process by which a radioactive atom’s nucleus breaks apart and forms different atoms

nuclear reaction in which an alpha particle is emitted

a particle emitted during alpha decay; composed of a helium nucleus containing two protons and two neutrons