OCR Physics A G484 Jan 2012 - The Newtonian World

If I was answering a question on when damping is a problem, I'd probably be inclined to mention a 'system' where more energy input would be required to maintain an oscillation/ vibration. Not sure exactly what I'm thinking of... but anything resistive like friction, could cause damping, right?

Not sure where I'm going with this :tongue:

Reply 183

Original post by shorty.loves.angels

If I was answering a question on when damping is a problem, I'd probably be inclined to mention a 'system' where more energy input would be required to maintain an oscillation/ vibration. Not sure exactly what I'm thinking of... but anything resistive like friction, could cause damping, right?

Not sure where I'm going with this :tongue:

Yup cos energy is transferred from the system as work done against friction in the form of heat :tongue:

Reply 184

Original post by wibletg

Yup cos energy is transferred from the system as work done against friction in the form of heat :tongue:

Or kinetic energy of other particles... example, an oscillation in water would transfer kinetic energy to water molecules.

Reply 185

Original post by shorty.loves.angels

Or kinetic energy of other particles... example, an oscillation in water would transfer kinetic energy to water molecules.

Surely that applies to solids too? :tongue:

Friction ----> Increase in KE of particles due to transference of heat between surfaces? (if we're really getting technical :wink:

)

(edited 12 years ago)

Reply 186

Original post by wibletg

Surely that applies to solids too? :tongue:

Friction ----> Increase in temperature due to transference of KE between particles? (if we're really getting technical :wink:

)

Haha wasn't getting that technical... and it was only an example :tongue:

I was thinking back to the question on G481 the other week that asked where the kinetic energy of a meteor collision (or something similar :tongue:

) would transfer to. We were discussing what the correct answer would be, I put heat energy and kinetic energy of other particles... a lot put sound.

Has anyone lurking around here done many of the Mechanics modules in maths? Considering taking one/ some of them and wondered if anyone would mind telling me a bit about the content of them compared to physics, pretty please.

Reply 187

Original post by shorty.loves.angels

Has anyone lurking around here done many of the Mechanics modules in maths? Considering taking one/ some of them and wondered if anyone would mind telling me a bit about the content of them compared to physics, pretty please.

I can speak for OCR M1-3

M1 is things like inclined planes, simple momentum, simple pulley systems and friction. (inclined planes is in G481, momentum is in G484).

M2 is things like calculating centre of mass, power equations, moments, horizontal circular motion, coefficient of restitution (horizontal circular motion crops up in G484)

M3 has SHM (G484), Hookes law (G481), vertical circular motion (G484), differential motion equations, impulse, momentum in 2 directions.

All of the exam boards will have most of the above in their mechanics modules, and the maths is harder than the maths you see in Physics but it's still do-able :tongue:

Reply 188

username896004

Original post by aquark

Can anyone define critical damping?

The minimum amount of damping required, such that the system is returned to equilibrium in the shortest possible time

Reply 189

High VOLTAGE

11

what's the exact definition of SHM because the marks schemes and books are confusing:
one says the acceleration is proportional to the displacement from equib position , acceleration is towards towards equib position.

the other : acceleration is proportional to displacement from equib position, acceleration is in the opposite direction to the midpoint

Reply 190

Ralphus J

Original post by High VOLTAGE

what's the exact definition of SHM because the marks schemes and books are confusing:
one says the acceleration is proportional to the displacement from equib position , acceleration is towards towards equib position.

the other : acceleration is proportional to displacement from equib position, acceleration is in the opposite direction to the midpoint

i say acceleration is directly proportional to displacement from equilibrium position. The acceleration is directed towards the equilibrium position. Like a BOSS i always get it right :cool:

Reply 191

Original post by High VOLTAGE

what's the exact definition of SHM because the marks schemes and books are confusing:
one says the acceleration is proportional to the displacement from equib position , acceleration is towards towards equib position.

the other : acceleration is proportional to displacement from equib position, acceleration is in the opposite direction to the midpoint

I think mid point is the max displacement... if so, it's the same thing.

I always put that acceleration's in the opposite direction to displacement as I understand it better than 'midpoint'

Reply 192

High VOLTAGE

11

Original post by ebmaj7

State and explain:

A situation where the high value of the specific heat capacity of water is useful / unuseful.

Useful : hot water bottle, or central heating system?

Reply 193