physics chapter 4

Question 1

define force

Answer 1

A push or a pull that acts on an object due to the interaction with another object

Question 2

define elasticity

Answer 2

Elasticity refers to the ability of a material to deform under an applied force and then return to its original shape when the force is removed. Elastic materials can be stretched or compressed to a certain extent without undergoing permanent deformation.

Question 3

define plasticity

Answer 3

Plasticity, on the other hand, refers to the ability of a material to undergo permanent deformation without breaking

Question 3

what is the hooke’s law

Answer 3

the extension of an object is directly proportional to the force that is applied to it provided the elastic limit is not exceeded

Question 4

How can you work out the extension

Answer 4

Extension= New length-original length

Question 5

how do we calculate the spring constant

Answer 5

k (spring constant) = F ( force) / x ( extension)

Question 6

define spring constant

Answer 6

the spring constant can be defined as the force per unit extension

Question 7

in which unit is the spring constant measured

Answer 7

newton per centimetre ( N/cm), and newton per metre ( N/m)

Question 8

what is the limit of proportionality

Answer 8

the point beyond which the extension is no longer directly proportional to the load

Question 9

what can the force change within its object

Answer 9

speed, direction, shape and size

Question 10

what is a resultant force

Answer 10

A resultant force is a single force that describes all of the forces operating on a body

Question 11

what does the single reluctant force determine

Answer 11

• The direction in which the object will move as a result of all of the forces
• The magnitude of the net force experienced by the object

Question 12

how do we tell if a force is balanced

Answer 12

Forces are balanced if multiple forces act in opposing directions with an equal magnitude in each direction

Question 13

how do we tell if a force is unbalanced

Answer 13

Forces are unbalanced if the effects of the forces acting in each plane do not cancel out

Question 14

how do we calculate the reluctant force

Answer 14

when the force is going the same direction, you sum the values up.
when the forces are going in opposite directions, then minus the smaller value from the bigger value

Question 15

define friction

Answer 15

friction is a force that impedes motion

Question 16

why is friction a resistive force

Answer 16

friction is a resistive force because it acts in the opposite direction to motion

Question 17

what are the types of friction

Answer 17

static friction, sliding friction and rolling friction

Question 18

define static friction

Answer 18

static friction is defined as the frictional force that acts between the surfaces when they are at rest with respect to eachother

Question 19

define rolling friction

Answer 19

rolling friction is defined as the force which resists the motion of a ball or wheel and is the weakest type of friction

Question 20

define drag forces

Answer 20

Drag forces are forces that oppose the motion of a body through a fluid (a gas or a liquid). Typical examples are the air resistance force experienced by a car or plane, or the resistance force experienced by a steel marble dropped into a jar of honey.

Question 21

define lever

Answer 21

A lever is a simple machine that can rotate freely about a fixed point

Question 22

define fulcrum

Answer 22

The pivot point about which the beam rests and moves freely. Since the beam can move freely, the fulcrum is also known as the lever’s turning point

Question 22

define load

Answer 22

The object on the beam that the lever tries to move, lift or turn around

Question 23

define effort

Answer 23

The force applied to lift or move the object, resulting in work

Question 23

define moment

Answer 23

The turning effect of a force about a pivot

Question 24

how do we calculate the moment

Answer 24

moment = force x perpendicular distance from pivot

Question 25

what is the unit for moment

Answer 25

newton metres

Question 26

what is the principle of moments

Answer 26

when the total clockwise moment is equal to the total anticlockwise moment, there is no resultant turning effect about a pivot. this is the principle of moments

Question 27

what happens when an object is in the equilibrium

Answer 27

when there is no resultant force and no resultant moment, an object is in equilibrium

Question 28

define centre of gravity

Answer 28

the centre of gravity of an object is the point through which the weight of the object acts

Question 29

what are the conditions of an object in its equilibrium

Answer 29

• The forces on the object must be balanced
• The sum of clockwise moments on the object must equal the sum of anticlockwise moments

Question 30

what are the types of equilibrium

Answer 30

stable, unstable and neutral