Further Mechanics 1&2 Flashcards
How to find the centre of mass of a lamina that has holes cut out
Find the centre of mass of the whole shape and of the cut out shape
Take moments, assuming the 2 shapes are point particles, the mass of the cut out shape should be negative
How to find the centre of mass of any system
Take moments about a point/line
Moment of whole system (Mass of whole system x Dist of CofM from pivot)
=
sum of moments of each component in system (Find CofM of components and x mass)
How to find the Centre of Mass of a uniform Triangular Lamina
Average of the 3 points
How to find the centre of mass of any rod
Midpoint of the rod
Where will the Centre of mass of any object with 1+ axis of symmetry be
On the axis of symmetry
At the point of intersection of the axis of symmetry
What happens when a lamina/framework is suspended freely from a fixed point
It will rest in equilibrium with the CofM directly below the fixed point it is suspended from
Define Centre of Mass
Point at which the whole point of the body can be considered to be concentrated
How to find the centre of mass of an arc
Where the center angle is 2α
Dist. from centre, along the axis of symmetry = rsin α / α
How to find the centre of mass of a sector
The centre angle is 2α
The dist. from the centre, along the axis of symmetry
= 2/3 x (rsin α / α )
What is Hooke’s Law
T = λx / L
λ = Modulus of elasticity
x = extension
L = Original length
T = Tension in string/spring
What is elastic potential energy
Work done to stretch/compress a string/spring
How to calculate Elastic Potential Energy
EE = λx2 / 2L
Easiest way to do horizontal circular motion questions
Resolve towards the centre of rotation
What happens to a particle at the point when it leaves its vertical circular motion
The force acting towards the centre of rotation, causing the circular motion, becomes 0
Particle acts as a projectile, moving under gravity
