physics chapter 4 Flashcards
define force
A push or a pull that acts on an object due to the interaction with another object
define elasticity
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.
define plasticity
Plasticity, on the other hand, refers to the ability of a material to undergo permanent deformation without breaking
what is the hooke’s law
the extension of an object is directly proportional to the force that is applied to it provided the elastic limit is not exceeded
How can you work out the extension
Extension= New length-original length
how do we calculate the spring constant
k (spring constant) = F ( force) / x ( extension)
define spring constant
the spring constant can be defined as the force per unit extension
in which unit is the spring constant measured
newton per centimetre ( N/cm), and newton per metre ( N/m)
what is the limit of proportionality
the point beyond which the extension is no longer directly proportional to the load
what can the force change within its object
speed, direction, shape and size
what is a resultant force
A resultant force is a single force that describes all of the forces operating on a body
what does the single reluctant force determine
- 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
how do we tell if a force is balanced
Forces are balanced if multiple forces act in opposing directions with an equal magnitude in each direction
how do we tell if a force is unbalanced
Forces are unbalanced if the effects of the forces acting in each plane do not cancel out
how do we calculate the reluctant force
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
define friction
friction is a force that impedes motion
why is friction a resistive force
friction is a resistive force because it acts in the opposite direction to motion
what are the types of friction
static friction, sliding friction and rolling friction
define static friction
static friction is defined as the frictional force that acts between the surfaces when they are at rest with respect to eachother
define rolling friction
rolling friction is defined as the force which resists the motion of a ball or wheel and is the weakest type of friction
define drag forces
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.
define lever
A lever is a simple machine that can rotate freely about a fixed point
define fulcrum
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
define load
The object on the beam that the lever tries to move, lift or turn around
define effort
The force applied to lift or move the object, resulting in work
define moment
The turning effect of a force about a pivot
how do we calculate the moment
moment = force x perpendicular distance from pivot
what is the unit for moment
newton metres
what is the principle of moments
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
what happens when an object is in the equilibrium
when there is no resultant force and no resultant moment, an object is in equilibrium
define centre of gravity
the centre of gravity of an object is the point through which the weight of the object acts
what are the conditions of an object in its equilibrium
- The forces on the object must be balanced
- The sum of clockwise moments on the object must equal the sum of anticlockwise moments
what are the types of equilibrium
stable, unstable and neutral
Forces can affect an object in different ways:
- Change in motion
- Change in size/shape
define inertia
the tendency of an object to stay at rest or preserve its state of motion
what is newton’s first law of motion
Every object will continue in its state of rest or of uniform motion along a straight line until it is acted by an unbalanced force.
how can we calculate the resultant force
resultant force = mass x acceleration
what is centripetal force
centripetal force is the force acting on a body moving in a curved path that is directed towards the centre of rotation
More centripetal force is needed if:
- the mass of the object is increased
- the speed of the object is increased
- the radius of the circle is reduced.
