- Created by: megan
- Created on: 16-05-12 19:34
Scalar or Vector?
Speed- Distance/Time = ms-1
Acceleration- Change in velocity/Time = ms-2
Force- Mass X Acceleration= Newton. Kgms-2
Pressure- Force/Area = pascal (Pa). Kgm-1s-2
Work- Force X Distance = Jouke. Kgm2s-2
Power- Work/ Time = Watt . Kgm2s-3
Newtons first law= an object will remain in a state of rest or continue to move with a constant velocity unless acted up by a resultant external force
Newtons second law= the acceleration of a body of constant mass is proportional to the resultant force applied to it and in the direction of the resultant force F=MA
Newtons third law= if body A exerts a force on body B. body b will exert an equal and opposite force on body a. third law paris mst: act on 2 seperate bodies, same type, same line, equal magnitude, opposite directions.
Work done=force X distance moved. (joules)
power = work done/time taken. (watts)
Average Velocity= Displacement/Time
Any change in velocty= Accerating. The magnitude of acceleration is a measure of the rate at which velocity changes.
Acceleration= Change in velocity/ Change in time.
in the absence of air resistance,all objects fall with acceleration- 9.81 ms-2
neglecting air resistance, the horizontal component of the initial velocity will remain constant.
Displacement time graphs- gradient=velocity, if gradient isnt straight= there is acceleration.
Instantaneous velocity is the gradient of the graph at a point. Can be measure by drawing a tangent on the line.
Velocity time graphs- gradient= acceleration.deceleration= a negative gradient. Area under graph= displacement.
Elastic deformation: will return to original dimensions when force is removed
Plastic: will remain deformed
Hard: Difficult to indent
Stiff: high young modulus
Tough: high energy density/ large plastic region/ able to absorb energy
Brittle: an object will shatter when subject to shocks, without deforming plastically.
Strong: high breaking stress/ can withstand large forces before it breaks
Malleable: hammered into thin sheets
Ductile: Can be drawn into wires without losing their strength
Hookes Law= up to a given load, the extension of a pring is directly proportional to the force applied to the spring. F= KX (k-spring constant)
Limit of proportionality- the point the material stops obeying hooks law. but would still return to its original shape if stress is removed.
elastic limit- at this point the material starts to behave plastically. at this point the material would no longer return to its original shape once the stress was removed.
Yield point- the stress at which a large amont of plastic deformation takes place with a constant or reduced load.
Work done= 1/2 X Max force X extention
Elastic strain energy= the area under the graph.
Stress=Force/Cross sectional area
Strain=Extension/ original length
Young modulus= stress/strain.
Energy density= work done/ volume = 1/2 X stress X strain = the area under a stress stain graph.
the hysteresis loop for a stress starin graph represents the energy per unit volume transferred to internal energy during the cycle.
Upthrust= a consequence of water pressre being greater below an immersed obect
upthrust= weight displaced = vpg
an object willfloat in a fluid if the upthrust is equal to its weight
laminar flow=no abrupt change in velocity or direction of flow lines. adjacent layersdo not cross over each other
turbulent= streamlines are no longer continuous
viscosity= the resistance of a fluid to flow
Resultant force= W-(U+F) If an object is accelerating downwards
viscous drag increases untill (u+f)= w << terminal velocity.