P5 Forces Flashcards
Definition
Vector
Scalar quantities
1 example
Vector-Quantity that contains magnitude and direction- Forces
Scalar-Quantity that contains magnitude and no direction-Speed
Definition and 2 types
Force
A force is a push or pull on a object that is caused by interacting with something.
They are either contact so must touch for the force to act.
Or non-contact so the object does not have to touch for the force to act.
Definition and units
Mass
Weight
Mass is the amount of particles in an object. Meausred in kilograms
Weight is the force acting on an object due to gravity. Measured in Newtons.
Units
Weight Equation
Weight(N)=Mass(Kg) x Gravitational Field(N/Kg)
Weight and Mass are directly proportional
Definiton and how to calculate
Resultant force
It is the overall force acting on an object. If forces act along the same line they are added up but if going the opposite way they are subtracted.
Equation and definition
Work done
W(J)=F(N) x s(m)
When a force moves along a distance energy is transferred so work is done.
Someone walks 4N north then 3N east.
Calculate the magnitude and direction of the resultant force
Resultant force is 5N and on a bearing of 037 degrees
Elastically deformed
Inelastically deformed
Elastically deformed-Can go back to original shape and length after force has been removed.
Inelastically deformed-Doesnt return to its original shape and length after force has been removed.
Elastic force equation and rules
F(N)=k(N/m) x e(m)
Extension is directly proportional to force butstops working when force is too great
Definiton
Limit of propotionality
The point in which extension is not directly propotional to the force.
Once past this the spring is permanetly deformed.
Definition and equation
Moment
Turning effect of a force.
Moment=F x d
2 factors to increase a moment for example in a spanner
A longer distance(spanner) means a larger moment.
To get the maximum moment you need to push at right angles to the spanner.
How do levers make it easier
Increase the distance from the pivot at which a force is applied.
Meaning less force is needed to get the same moment.
Levers make it easier to do work.
What do gears do
They transmit rotational effects.
Smller cogs turn faster.
Though larger cogs have a bigger moment as the distance to the pivot is greater
Pressure equation and description of pressure in a fluid
P=F/A
Pressure of a fluid means a force is exerted at right angles to any surface in contact with the fluid
Pressure in a liquid and theory
P= height x density x gravitational field strength
The more dense a liquid is the more particles it holds in a given space. More particles are able to collide so the pressure is higher.
As the depth of a liquid increases. The number of particles above that point increases.
Upthrust
This is the resultant force when an object is submergered in a fluid.
If an object is less dense than the fluid it will displace the same wieght of fluid so it will float.
If an object is more dense than the fluid it is unable to displace enough fluid so sinks.
Theory of atmospheric pressure
As height increases pressure decreases.
Fewer air molecules to collide and the air is less dense.
