Physics Dictionary

Question 1

Displacement

Answer 1

change in position

Question 2

Distance

Answer 2

length of path followed

Question 3

Acceleration

Answer 3

the rate of change of velocity

Question 4

Instantaneous velocity

Answer 4

the average velocity obtained during an interval of time that is very, very small.

Question 5

Instantaneous speed

Answer 5

magnitude of the instantaneous velocity

Question 6

Average speed

Answer 6

total distance travelled divided by the total time taken.

Question 7

Average velocity

Answer 7

change in position (i.e. the displacement) divided by the time taken

Question 8

Acceleration of free fall

Answer 8

an acceleration caused by the attraction between the Earth and the body.

Question 9

Terminal Speed

Answer 9

body moving at constant speed

Question 10

Weight

Answer 10

the result of the gravitational attraction between the mass m of a body and the mass of the planet on which the body is placed

Question 11

Tension

Answer 11

The force that arises in any body when it is stretched

Question 12

Hooke’s Law

Answer 12

The relation between tension and extension

Question 13

Drag Force

Answer 13

forces that oppose the motion of a body through a lid (a gas or a liquid)

Question 14

Upthrust

Answer 14

force experienced by any object placed in a fluid

Question 15

Free-body Diagram

Answer 15

a diagram showing the magnitude and direction of all the forces acting on a chosen body.

Question 16

Newton’s first law

Answer 16

When the net force on a body is zero, the body will move with 
constant velocity (which may be zero).

Question 17

Order of magnitude

Answer 17

an estimate given as just a power of 10

Question 18

absolute uncertainty

Answer 18

a quantity giving the extremes a measured value falls within

Question 19

absolute zero

Answer 19

the temperature at which all random motion of molecules stops

Question 20

absorption spectra

Answer 20

the set of wavelengths of photons absorbed by a substance

Question 21

albedo

Answer 21

the ratio of scattered to incident intensity of radiation

Question 22

ammeter

Answer 22

an instrument that measures the electric current through it

Question 23

angular speed

Answer 23

the ratio of angle turned to time taken