Mechanics Definitions

Question 0

Vector

Answer 0

A quantity with both magnitude and direction.

Question 1

Scalar

Answer 1

A quantity with only one magnitude.

Question 2

Displacement

Answer 2

The distance moved by an object in a particular direction (in the direction of the force).

Question 3

Instantaneous Speed

Answer 3

The speed of an object measured at a particular point in time.

Question 4

Average Speed

Answer 4

The total distance travelled, by an object, divided by the total time taken.

Question 5

Velocity

Answer 5

The rate of change of displacement of an object measured in ms-1.

Question 6

Acceleration

Answer 6

The rate of change of velocity of an object measured in ms-2.

Question 7

Newton

Answer 7

The force that will give a 1kg mass an acceleration of 1ms-2 in the direction of the force. 1N = 1kgms-2

Question 8

Torque of a Couple

Answer 8

The product of one of the forces in a couple and the perpendicular distance between them (unit = Nm).

Question 9

Couple

Answer 9

A pair of equal parallel forces acting in opposite directions on an object.

Question 10

Moment

Answer 10

The moment of a force about a point is the magnitude of the force multiplied by the perpendicular distance of the point from the line of force (unit = Nm).

Question 11

Thinking Distance

Answer 11

The distance travelled from the moment the driver sees the need to brake and the point they start braking.

Question 12

Braking Distance

Answer 12

The distance travelled by an object from applying the brakes until coming to a complete stop.

Question 13

Stopping Distance

Answer 13

The sum of the braking and thinking distance.

Question 14

Work Done

Answer 14

Work done = force x distance moved in the direction of force.

Question 15

Joule

Answer 15

The energy transferred in moving a force of 1N moving through a distance of 1m.

Question 16

Power

Answer 16

The rate at which work is done. Unit Js-1 or W.

Question 17

Watt

Answer 17

1J of energy being transferred per second.

Question 18

Stress

Answer 18

The force acting per unit cross sectional area.

Question 19

Strain

Answer 19

The deformation produced (extension or compression) per unit length by tensile or compressive forces.

Question 20

Young’s Modulus

Answer 20

The ratio of stress to strain caused by compressive or tensile forces, provided Hooke’s Law is obeyed.

Question 21

Ultimate Tensile Strength (breaking stress)

Answer 21

The value of stress at which a material will break.

Question 22

Elastic Deformation

Answer 22

A material which will return to its original shape and size when deforming forces are removed.

Question 23

Plastic Deformation

Answer 23

The deformation of a material beyond the material’s elastic limit.

Question 24

Density

Answer 24

Mass per unit volume.

Question 25

Pressure

Answer 25

Force per unit contact area.

Question 26

Conservation of Energy

Answer 26

Energy cannot be created nor destroyed. It can only be transformed from one form to another.