4 Forces In Action Flashcards
F=ma
Force = mass x acceleration
Definition of a Newton
The force needed for a mass of 1kg to have an acceleration of 1 ms^-2 in a particular direction
W=mg
Weight = mass x gravity
What happens to the mass of an object as it approaches the speed of light
Mass increases
Centre of mass
The point through which an objects total weight acts
Weight
The gravitational force acting on an object through its center of mass
Friction
The force that arises when two surfaces rub against each other
Drag
The resistive force on an object travelling through a fluid
Tension
The force within a stretched cable or rope
Upthrust
An upward buoyancy force acting on an object when it is in a fluid
Normal contact force
A force arising when one object rests against another object
What is the relationship between drag and speed
Drag is directly proportional to speed^2
Terminal velocity
When a drag force on the object is equal and opposite to its weight
Moment
The turning effect of a force about some axis or point
M=Fx
Moment = force x perpendicular distance from the point of rotation
Base SI units of momentum
Kg m^2 s^-2
The principle of moments
For a body in rotational equilibrium the sum of the anticlockwise moments about any point is equal to the sum of the clockwise moments about the same point
Couple
Two equal but opposite parallel force which act along different lines
Torque = Fd
Torque = one of the forces x perpendicular distance between forces
Torque
The moment of a couple
What is the average atmospheric pressure
101kPa
p = h rho g
Pressure = height x density x acceleration due to free fall
Upthrust = rho g V
Upthrust = density x acceleration due to free fall x volume
Archimedes principle
The Upthrust exerted on a body immersed in a fluid, whether fully or partially submerged is equal to the weight of the fluid that the body displaces
