Mechanics Definitions

Question 0

*Displacement

Answer 0

Distance moved in a stated direction (m)

Question 1

*Scalar

Answer 1

A quantity with magnitude (size) but not direction

Question 2

*Acceleration

Answer 2

Rate of change of velocity (ms^-2)

Question 3

*Vector

Answer 3

A quantity with both magnitude (size) and direction

Question 4

*Velocity

Answer 4

Displacement per unit time (vector) (ms-1)

Question 5

*One Newton (N)

Answer 5

The force that causes a mass of 1kg to have an acceleration of 1ms-2

Question 6

*speed

Answer 6

Distance per unit time (scalar) (ms-1)

Question 7

*instantaneous speed

Answer 7

The speed at a given instant of time. The gradient of displacement-time graph at that instant. (ms-1)

Question 8

*couple

Answer 8

A pair of equal and parallel but opposite forces, which tends to produce rotation only

Question 9

*moment of a force

Answer 9

The force multiplied by the perpendicular distance from a stated point (usually the pivot) Nm

Question 10

*One joule (J)

Answer 10

the work done by a force of one newton when its point of application moves one metre in the direction of the force

Question 11

*gravitational potential energy (J)

Answer 11

The energy stored in an object by virtue of its position in a gravitational field (and the work that object can do)

Question 12

Density

Answer 12

Mass per unit volume (kgm-3)

Question 13

Energy

Answer 13

The stored ability to do work

Question 14

kinetic energy (J)

Answer 14

The work an object can do by virtue of its speed

Question 15

Pressure

Answer 15

Force per unit area (Nm-2 or Pa)

Question 16

Conservation of energy

Answer 16

energy may be converted from one form to another, but cannot be created or destroyed

Question 17

Power (W)

Answer 17

The rate of doing work

Question 18

One watt (W)

Answer 18

One joule per second

Question 19

Terminal velocity

Answer 19

When the net forces on a falling object are zero I.e. The drag equals the weight

Question 20

Hooke’s law

Answer 20

The extension of an elastic body is proportional to the force that causes it

Question 21

Equilibrium

Answer 21

When the net force and the net moment on an object are zero

Question 22

Stopping distance

Answer 22

The sum of the thinking distance and the braking distance

Question 23

Elastic deformation

Answer 23

Produces a straight line on a tension-extension graph, up to the elastic limit

Question 24

Principle of moments

Answer 24

When the sum of the clockwise moments equals the sum of the anticlockwise moments

Question 25

Young’s modulus

Answer 25

The ratio between the stress and strain for a material

Question 26

Plastic deformation

Answer 26

Produces a curved line on a tension-extension graph, after the elastic limit

Question 27

Work done

Answer 27

Force x distance, where distance is in the direction of the force