Mechanics Flashcards
Force
An interaction that acts to change the velocity of an object
Inextensible
Does not stretch
Instantaneous accelaration
Acceleration at a specific point in time
Instantaneous velocity
Velocity at a specific point in time
Instantaeously at rest
An object for whom v=0
Light
When an object’s weight is small enough to be negligible and so can be ignored in calculations
How do you find the acceleration (a) of a particle with non-constant accelaration?
Differentiate the velocity (v)
For a particle with non-constant acceleration how do you find the velocity (v)?
Differentiate the distance (x) or integrate the acceleration (a)
On a velocity time graph…
1) The acceleration is the gradient
2) The distance travelled equals the area between the graph and the t-axis
3) The change in displacement can be found be subtracting the area below the axis from the area above the axis
What assumptions does the constant acceleration model require?
1) Air resistance can be ignored (true if the object is modelled as a particle)
2) g is constant (true for small heights)
What is Newton’s second law?
F = ma
What is Newton’s third law?
If object A exerts a force on object B, then object B exerts a force on object A, with the same magnitude but opposite direction
Which way does thrust act ?
Outwards
Which way does tension act?
Inwards
What modelling assumptions are made about a string connecting two particles?
1) Inextensible (so the magnitude of the acceleration and velocity of each connected particle are the same)
2) Light (so the mass of the string is ignored and the tension of the string is the same throughout)
