Physics Definitions

Question 1

Momentum

Answer 1

The product of an object’s mass and it’s velocity (p=mv)

Question 2

Newton’s 2nd law of motion in terms of momentum

Answer 2

The net/resultant force acting on an object is equal to the rate of change of momentum of the object in the direction of the net force.

Question 3

The principle of conservation of linear momentum

Answer 3

The total linear momentum of an isolated system remains constant.

Question 4

Elastic collisions

Answer 4

Collisions in which both momentum and kinetic energy are conserved

Question 5

Inelastic collisions

Answer 5

Collisions in which only momentum is conserved

Question 6

Impulse

Answer 6

The product of the resultant/net force acting on an object and the time the net force acts on the object

Question 7

Projectile

Answer 7

An object which has been given an initial velocity and then moves under the influence of the gravitational force only.

Question 8

Free-fall

Answer 8

Motion during which the only force acting on an object is the gravitational force.

Question 9

Work-energy theorem

Answer 9

The work done on an object by a net force is equal to the change in the object’s kinetic energy. (Wnet=^Ek)

Question 10

Conservative force

Answer 10

A force for which the work done in moving an object between points is independent of the path taken.

Question 11

Non-conservative force

Answer 11

A force for which the work done in moving an object between two points depends on the path taken.

Question 12

Principle of conservation of mechanical energy

Answer 12

The total mechanical energy in an isolated system remains constant

Question 13

Power

Answer 13

The rate at which work is done or energy is expended.

Question 14

Doppler effect

Answer 14

The perceived change in frequency (or pitch) of the sound detected by a listener because the sound source and the listener have different velocities relative to the medium of sound propagation.

Question 15

Coulomb’s law

Answer 15

The magnitude of the electrostatic force exerted by one point charge on another point charge is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them.

Question 16

Electric field

Answer 16

A region of space in which an electric charge experiences a force.

Question 17

Direction of an electric field at a point

Answer 17

The direction that a positive test charge would move if placed at that point.

Question 18

Electric field strength at a point

Answer 18

The electrostatic force experienced per unit positive charge placed at that point

Question 19

Ohm’s law

Answer 19

The potential difference across a conductor is directly proportional to the current in the conductor at a constant temperature.

Question 20

Power

Answer 20

The rate at which work is done

Question 21

1 kilowatt-hour

Answer 21

The use of 1 kilowatt of electricity for 1 hour

Question 22

Emf

Answer 22

The maximum energy provided by a battery per unit charge passing through it.

Question 23

Rms for an alternating voltage

Answer 23

The rms potential difference is the AC potential difference which dissipates/produces the same amount of energy as an equivalent DC potential difference.

Question 24

Rms current

Answer 24

The alternating current which dissipates/produces the same amount of energy as an equivalent direct current.

Question 25

Photoelectric effect

Answer 25

The process whereby electrons are ejected from a metal surface when light of a suitable frequency is incident on that surface.

Question 26

Threshold frequency

Answer 26

The minimum frequency of light needed to emit electrons from a certain metal surface.

Question 27

Work function

Answer 27

The minimum energy that an electron in the metal needs to be emitted from the metal surface.

Question 28

Atomic absorbtion spectrum

Answer 28

An atomic spectrum that is formed when certain frequencies of electromagnetic radiation passing through a substance are absorbed.
The spectrum observed is a continuous spectrum with dark lines where characteristic frequencies of light were removed.

Question 29

An atomic emission spectrum

Answer 29

An atomic emission spectrum is formed when certain frequencies of electromagnetic radiation are emitted due to an atom making a transition from a higher energy state to a lower energy state.
The spectrum observed is a line spectrum with only a few colored lines of frequencies unique to the type of atom that is producing the emission lines.

Question 30

Newton’s 1st law of motion

Answer 30

An object will remain in it’s state of rest or motion at a constant velocity unless acted upon by a non-zero net/resultant force.

Question 31

Newton’s 2nd law of motion

Answer 31

When a net force acts on an object, the object will accelerate in the direction of the force at an acceleration directly proportional to the force and inversely proportional to the mass of the object.

Question 32

Newton’s 3rd law of motion

Answer 32

When object A exerts a force on object B, object B simultaneously exerts a force that is equal in magnitude and opposite in direction on object A

Question 33

Newton’s law of universal gravitation

Answer 33

Every body in the universe attracts every other body wihh a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

Question 34

Weight

Answer 34

The gravitational force that the Earth exerts on any object on or near it’s surface.

Question 35

Normal force

Answer 35

The force or component of force which a surface exerts on an object with which it is in contact, and which is perpendicular to the surface.

Question 36

Frictional force

Answer 36

The force that opposes the motion of an object and which acts parallel to the surface.

Question 37

Static frictional force

Answer 37

The force that opposes the tendency of motion of a stationary object relative to a surface.

Question 38

Kinetic frictional force

Answer 38

The force that opposes the motion of a moving object relative to a surface.

Question 39

Inertia

Answer 39

The resistance of an object to any change in its state of motion.

Question 40

Isolated system

Answer 40

A system on which the resultant/net external force is zero.