physics definitions

Question 1

state Newton’s first law

Answer 1

An object continues in a state of rest or uniform (moving with constant) velocity unless it is acted upon by a net or resultant force

Question 2

describe inertia

Answer 2

the property of an object that causes it to resist a change in its state of rest or uniform motion

Question 3

state newton’s second law

Answer 3

when a net force, fnet, is applied to an object of mass, m, it accelerates in the direction of the net force. The acceleration, a, is directly proportional to the net force and inversely proportional to the mass

Question 4

state newtons third law

Answer 4

when object A exerts a force on object B, object B simultaneously exerts an oppositely directed force of equal magnitude on object B

Question 5

state newton’s law of gravity

Answer 5

every particle with mass in the universe attracts every other particle with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres

Question 6

state Coulomb’s law

Answer 6

Two point charges in free space or air exert forces on each other. The force is directly proportional to the product of the charges and inversely proportional to the distance between the charges

Question 7

define magnetic flux linkage

Answer 7

the product of the number of turns on the coil and the flux through the coil

Question 8

state faradays law

Answer 8

the emf induced is directly proportional to the rate of change of magnetic flux (flux linkage)

Question 9

state lenz’s law

Answer 9

the induced current flows in a direction so as to set up a magnetic field to oppose the change in magnetic flux

Question 10

define emf

Answer 10

the total energy supplied per coulomb of charge by the cell

Question 11

state Ohm’s law

Answer 11

current through a conductor is directly proportional to the potential difference across the conductor at constant temperature

Question 12

state the work energy theorum

Answer 12

work done by a net force on an object is equal to the change in the kinetic energy of the object

Question 13

define power

Answer 13

the rate of change at which work is done

Question 14

define work

Answer 14

the product of the displacement and the component of the force parallel to the displacement

Question 15

state the conversation of energy

Answer 15

the total energy in a system cannot be created nor destroyed, only transformed from one form to another

Question 16

state the law of conservation of linear momentum

Answer 16

the total linear momentum of an isolated system remains constant

Question 17

define weight

Answer 17

the gravitational force the earth exerts on any object on or near its surface

Question 18

define normal force

Answer 18

the perpendicular force exerted by a surface on a object contact with it

Question 19

vector

Answer 19

physical quantity that has both magnitude and direction

Question 20

displacement

Answer 20

a change in position

Question 21

speed

Answer 21

the rate of change of distance

Question 22

velocity

Answer 22

the rate of change of displacement

Question 23

acceleration

Answer 23

the rate of change of velocity

Question 24

frictional force

Answer 24

the force that opposes the motion of an object

Question 25

linear momentum

Answer 25

the product of the mass and velocity of an object

Question 26

newtons second law in terms of momentum

Answer 26

the net force acting on an object is equal to the rate of change of momentum

Question 27

elastic collision

Answer 27

a collision in which both momentum and kinetic energy is conserved

Question 28

inelastic collision

Answer 28

a collision in which only momentum is conserved

Question 29

impulse

Answer 29

the product of the net force and the contact time

Question 30

gravitational potential energy

Answer 30

the energy an object possesses due to its position relative to a reference point

Question 31

kinetic energy

Answer 31

the energy an object has as a result of the object’s motion

Question 32

mechanical energy

Answer 32

the sum of gravitational potential and kinetic energy at a point

Question 33

principle of conservation of mechanical energy

Answer 33

in the absence of air resistance or any external forces, the mechanical energy of an object is constant

Question 34

gravitational field

Answer 34

the force acting per unit mass

Question 35

potential difference

Answer 35

the work done per unit positive charge

Question 36

current

Answer 36

the rate of flow of charge

Question 37

diode

Answer 37

a component that only allows current to flow in one direction

Question 38

threshold frequency

Answer 38

the minimum frequency of incident radiation at which electrons will be emitted from a particular metal

Question 39

work function

Answer 39

the minimum amount of energy needed to emit an electron from the surface of a metal