Module 3 Flashcards
How is instantanous speed found from a distance time graph
Finding gradient of tangent
Define acceleration
Rate of change opf velocity dv/dt
How to determine acceleration from a velocity time graph
Gradient
How to determine displacement from velocity time graph
Area underneath (sometimes by counting squares)
How to calculate stopping distance
Thinking distance - Braking distance
How to calculate thinking distance
Speed x reaction time
3 methods that can be used to accurately determine g
Electromagmet and trapdoor
Lightgates
Taking pictures
Equation linking mass and weight
W=mg
What can be used ton determine the centre of gravity fro 2D objects
Plum line
(weight on a string - when it comes to rest at the centre of gravity)
Define terminal velocity
When the drag force of the object is equal and opposite to its weight
Define moment
Force x perpendicular distance
moment = fx
What is the principle of moments
For a body in roational equalibrium, the sum of the anticlockwise moments about a point is equal to the sum of the cockwise moents about the same point
Define couple
A pair of equal and opposite forces that bare parralel along different lines
Define torque
Moment of a couple
How to calculate torque
One of the forces x perpendicular seperation between forces
Torque = fd
Equation for upthrust
Uprthrust = Axpg
State Archemedes 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.
Equation for work done
Force x distance (in direction of foce)
State the principle of conservation of energy
The total energy in a closed system remains constant: energy can never be created or destroyed only transferred from on form to another
Equation for GPE
GPE = mgh
Define elastic deformation
The spring will retern to its origional length once the force is removed
Define plastic deformation
Permanent structural chanes to the spring occur and it does not return to its origional length when the force is removed
State hookes law
The extension of the spring is directly proportional to the force applied as long as the elastic limit of the spring is not exceeded.
What is k in f=kx
Force constant of the spring
Define brittle
Elastic behaviour up to breaking point
Define ductile
Elastic and plastic regions before the material breaks
Newtons 1st law
An object will remain at rest or continue to move with constant velocity unless acted upon by a resultant force
Newtons 3rd law
If a body A exerts a force on body B then body B exerts and equal and opposite force on body A
Law of conservation of momentum
For a system of interacting objects, the total momentum in a specified direction remains constant, as long as no external forces act on the system
What is conserved in an elastic collision
Kinetic energy
Newtons 2nd law
The net force acting on an object is directly proportional to the rate of change of its momentum and is in the same direction
Equation for newtons 2nd law
F=dp/dt
Rate of change of momentum
Define impulse
Change in momentum (Fxt)
