Materials

Question 1

Breaking Stress

Answer 1

The maximum stress that an object can withstand before failure occurs

Question 2

Brittle

Answer 2

A brittle object will show very little strain before reaching its breaking stress

Question 3

Centre of mass

Answer 3

The single point through which all mass of an object can be said to act

Question 4

Conservation of energy

Answer 4

Energy cannot be created or destroyed, only transferred in different forms

Question 5

Conservation of momentum

Answer 5

The total momentum of a system before an event must be equal to the total momentum afterwards assuming no other force has acted upon it

Question 6

Couple

Answer 6

Two equal and opposite parallel forces that act on an object through different lines of action it has the effect of causing a rotation without translation

Question 7

Density

Answer 7

The mass per unit volume of a material

Question 8

Efficiency

Answer 8

The ratio of useful output to total input

Question 9

Elastic behaviour

Answer 9

If a material deforms with elastic behaviour it will return to its original shape when deforming forces are removed. The object will not be permanently deformed

Question 10

Elastic limit

Answer 10

The force beyond which an object will no longer deform elastically, instead deforming plastically. Beyond the limit objects will not return to their original shape

Question 11

Elastic strain energy

Answer 11

The energy stored in an object when it’s stretched. It’s equal to work done to stretch the object and can be determined from the area under a force-extension graph

Question 12

Equillibrium

Answer 12

Both resultant force and resultant moment acting on the object are equal to 0

Question 13

Hooke’s Law

Answer 13

The extension of an elastic object is directly proportional to the force applied to it up to the object’s limit of proportionality

Question 14

Impulse

Answer 14

The change of momentum of an object when a force acts on it. It’s equal to the product of the force acting on the object and the length of the time over which it acts

Question 15

Inelastic collision

Answer 15

A collision in which the total kinetic energy of the system before the collision is not equal to the kinetic energy of the system after the collision

Question 16

Moment

Answer 16

The product of a force and the perpendicular distance from the line of action of the force of the pivot

Question 17

Momentum

Answer 17

The product of an object’s mass and velocity

Question 18

Newton’s 1st law

Answer 18

An object in motion stays in motion unless acted upon by a resultant force

Question 19

Newton’s 2nd Law

Answer 19

F=ma

Question 20

Newton’s 3rd law

Answer 20

Every action has an equal opposite reaction

Question 21

Plastic behaviour

Answer 21

If a material deforms with plastic behaviour, it will not return to its original shape. The object is permanently deformed.

Question 22

Principle of moments

Answer 22

For an object to be in equilibrium, the sum of the clockwise moments around a point must be equal to the sum of anticlockwise moments

Question 23

Scalar

Answer 23

A scalar quantity is one that only has magnitude not direction i.e length, temp, mass

Question 24

Spring constant

Answer 24

The constant of proportionality for the extension of a spring under a force. The higher the spring constant, the greater the force needed to achieve a given extension.

Question 25

Stiffness

Answer 25

A measure of how difficult it is to stretch a given object

Question 26

Tensile strain

Answer 26

The ratio of an objects extension to its original length. It’s a ratio of two lengths and has no unit

Question 27

Tensile stress

Answer 27

The amount of force acting per unit area. Measured in Pa

Question 28

Terminal speed

Answer 28

The maximum speed of an object that occurs when the resistive and driving forces are equal

Question 29

Vector

Answer 29

Has both magnitude and direction i.e velocity displacement acceleration

Question 30

Young’s modulus

Answer 30

The ratio of stress to strain for a material (Pa)