Physics Unit 2 Summary notes
- Created by: sammyfudge
- Created on: 22-02-14 16:37
Physics Unit 2
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Topic 1
o Gradient on a distance-time graph = speed
o Long-distance vehicles are fitted with recorders called Tachographs, to check that drivers don’t drive too long
o Velocity is speed in a given direction
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The acceleration(m/s2) of an object is its change of velocity per second
o Constant speed
o Gradient on a velocity-time graph = acceleration
o The area under the line on a velocity-time graph = distance travelled
o Topic 2
o A force can change the shape of an object or change its motion or its state of rest
o When 2 objects interact they always exert equal and opposite forces on each other
o Force is measured in newtons (N)
o engine force / motive force due to friction
o Resultant Force = the combined effect of the forces acting on an object
o If resultant force = zero, object remains stationary / constant velocity
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Thrust, air resistance, friction
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The greater the mass of an object, the smaller its acceleration is for a given force
o High speed, poor weather conditions (icy) and poor maintenance (brakes and tyres) all increase the braking distance.
o Poor reaction time (tiredness, alcohol, drugs and mobile phones) and high speed both increase the thinking distance.
o The gravitational force of attraction slightly weaker at the equator than at the poles
o Weight = The force of gravity on an object
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Mass = The quantity of matter in an object; a measure of the difficulty of changing the motion of an object
o If an object falls with no other forces acting on it, the resultant force on it is its weight. It accelerates downwards at a constant acceleration of 10m/s2
o fluid drags on an object
o drag force increases with speed
o acceleration of an object decreases as it falls, because the drag force increases as it speeds up, so the resultant force decreases, so the acceleration decreases
o when drag force = weight , reaches constant velocity called terminal velocity, and the resultant force is zero, so the acceleration is zero
o The terminal velocity of a falling object is the velocity it reaches when it is falling in a fluid. The weight is then equal to the drag force on the object.
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An elastic object regains its shape when the forces deforming it are removed
o Hooke’s Law; The extension of a string is directly proportional to the force applied, provided its limit of proportionality is not exceeded
o The spring constant of a spring is the force per unit extension…
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