PHYSICS Flashcards
(179 cards)
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9.1 Units in Movement1.1 Units in Movement _ADV.pptx
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Distance - the measure of how far apart objects are from each other
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Speed - the measure of how fast something moves
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Average Speed - the measure of how fast something moves overall
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Instantaneous Speed - speed at a particular instant
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Standard International Units (SL) - m/s (meters/per second
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- Cars - km/h (kilometers/hour)
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- Speed - km/h → m/s = divide by 3.6
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- Speed - m/s → km/h = multiply by 3.6
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Graphing Motion
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- Distance time graph shows how far an object travels as time progresses
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- Steep slope - object is moving fast
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- Gentle slope - object is moving slow
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3. Flat line - object that has stopped
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* The gradient/slope = object's average speed over a time interval
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* Steep slopes = object covers a greater distance
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* Speed-time graph - shows an object’s speed changes overtime/ over a period of time
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1. Flat line = constant speed
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2. Line rising = increase in speed
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3. Line falling = decrease in speed
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* Area located below a speed-time graph = the distance that object travelled up to a given point
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* Slope = acceleration
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9.2 Units in Movement 1.2 Acceleration_ADV.pptx
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Acceleration = the rate at which an object changes its velocity (a speed and direction)
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Terminal velocity = the constant speed that a free falling object eventually reaches when the resistance of the medium (i.e resistance) through which it is falling prevents further acceleration
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Resistance = the act of opposing or withstanding something
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Average Acceleration formula:
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* Average acceleration = change in speed/time | final speed - initial speed/time | a = v - u/t
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* Final speed = initial speed + (average acceleration x time taken) | v = u +at
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9.3 Newton’s Law of Motion 1.3 Newton's laws of motion_amended.pptx
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Galileo Galilei (1561 - 1642) - realised objects stop because the force of friction acts in the opposite direction to their direction of motion
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Isaac Newton (1642 - 1727) - developed Galileo's ideas further and developed the three laws of motion
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Newton’s first law of motion
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* An object at rest - remains at rest
unless acted upon by a force
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* A moving object - continues to move at the same speed at the same direction
unless an unbalanced force acts upon it
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* An object's inertia is the tendency to resist any change in motion
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- A larger mass object - the greater its inertia - the hard it is to change its motion
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* Balanced force - forces on opposite sides are equal
back = front
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* Unbalanced forces cause a change in speed
direction or motion. Forces that are not equal on opposite sides
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* Train or bus that suddenly accelerates/stops/turns
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* Car accidents
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Newton’s second law of motion
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* An object will accelerate in the direction of an unbalanced force acting upon it
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* The size of the object's acceleration depends on the mass of it and the size of the force acting against it
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* Larger force is needed to accelerate a heavy load than a lighter load
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* Larger force is required to accelerate something at a faster rate
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Fnet = m x a
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* The acceleration an object experiences due to a force depends upon its mass
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* Low mass objects will travel with much greater acceleration than a more massive object
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Forces
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* There is usually more than one force acting on an object any one time
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* a = Fnet/m
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Newton’s third law
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* For every action
there is an equal and opposite reaction force
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9.4 Energy Changes 1.4 Energy changes_Amended.pptx
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Kinetic Energy
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* The energy of a moving object
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* The amount of kinetic energy an object experiences depends upon its mass and speed
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Objects..
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* Mass x2 = KE x2
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* Speed x2 = KE x4
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* The heavier the object and the greater the speed - the more energy it will transfer to the object it collides with - the greater the damage
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Potential Energy (stored energy)
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* Energy that an object has because of its position or structure
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* Gives objects the capacity to make things happen/cause change
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* An object positioned above the ground has gravitational potential energy
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* Greater mass object - the greater the gravitational potential energy
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Elastic potential energy
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* Energy from an object that is stretched or compressed
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* One the spring/object is released then the energy is converted into kinetic energy
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* Stretched object → released → goes back into original shape
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Energy calculations: Kinetic Energy
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* An object's kinetic energy is related to its mass and speed
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* Kinetic Energy = ½ mass x speed2 |Ek = ½ mv2
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* EK - Joules (j) | m - kg | v - m/s
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Energy Calculations: gravitational potential energy
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* The GPE of an object is related to the mass of the object and its height above ground
and the the acceleration due to gravity at this point
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* GPE = mass x acceleration to to gravity (9.8 kg) x height |EP = mgh
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Conservation of energy
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* Energy may be transferred from one object to another
but it is never created or destroyed
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* Energy at the start = energy at the bottom
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Energy transfer and transformations: car crashes
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* Moving car (kinetic energy)
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- metal deformation (heat energy)
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- noise (sound)
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- springiness in the car structure (elastic potential energy
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Energy transfer and transformations: pendulums
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Energy efficiency
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* The efficiency of an energy transfer is a measure of how much useful energy is produced
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* Small energy is ‘lost’ because it changes into non-useful forms such as heat and sound
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* Energy used (input) - only some useful energy
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* Useful energy (output)
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* Electrical Energy → kinetic energy + sound energy + heat energy
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* Efficiency = useful energy output/ total energy input x 100%
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Physics Test Notes
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* Use a pen
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* Average speed - m/s
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* Deceleration
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* Acceleration
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* Free body diagram
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* Everyday examples →forces on objects
how
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* Speed time graph
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* Energy efficiency
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* How is energy lost?
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* Potential energy calc
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* Kinetic energy calc
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* Speed calc
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* Assumption calc
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* E (gp) = mgh
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* Why is gravity different in the moon
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* Gravity strength in the moon
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* Newton's 3 Laws. 1st
2nd
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* Joules
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* The effect of mass and speed on kinetic energy
