Flashcards
P2.1 - Motion
Cards in this deck (106)
- 1what is speed?how fast you go
- 2what is velocity?how fast you go and what direction you are going in
- 3what is the formula for speed?speed = distance / time
- 4what is acceleration?how fast velocity changes
- 5acceleration is a vector what does this mean?it has a magnitude (how fast it is changing) and a direction
- 6how do we show decelerationas negative acceleration: eg -2
- 7what is the formula for acceleration?change in velocity
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time taken - 8what is the units for acceleration?m/s^2
- 9what does the gradient represent on a distance-time graph?the speed
- 10what does a flat line show on a distance time graph?a stop
- 11what does a steeper gradient represent in a distance-time graph?faster speed
- 12what do curves represent on a distance-time graph?acceleration/deceleration
- 13what does a downhill line represent on a distance-time graph?going back to the starting position
- 14what does the gradient represent on a velocity-time graph?acceleration
- 15what does a flat line represent on a velocity time graph?constant speed
- 16what does a steeper gradient represent on a velocity time graph?greater acceleration/deceleration
- 17what does an uphill line represent on a velocity-time graph?acceleration
- 18what does a downhill line represent on a velocity-time graph?deceleration
- 19what does the area under a velocity time graph represent?the distance travelled
- 20what does a curve represent on a velocity-time graph?changing acceleration/deceleration
- 21what is gravity?the force of attraction between all masses
- 22what does gravity do? (2)*makes things accelerate to the ground at the same acceleration of 10m/s^2
*gives everything a weight - 23what is mass?amount of stuff in an object
- 24what is mass measured in?kg or g
- 25what is weight?caused by the pull of gravity
- 26what is weight measured in?N
- 27why can weight change but mass doesn't?different weights due to different gravity strengths (on different planets) but always has the same amount of stuff in it
- 28what are the gravitational field strengths for: *the Earth *the Moon*10 N/kg
*1.6 N/kg - 29what is the formula for weight?weight = gravitational field strength x mass
- 30what is a resultant force?the overall force acting on an object
- 31how many forces is there at least acting on all objects?two
- 32what is the reaction force?the force pushing in the opposite direction to the force applied
- 33what is the action force?thethe force applied
- 34when the resultant force is 0 what is happening?the object is stationary at a constant speed
- 35when the resultant force is 0, what is happening with the action and reaction force?the action force = the reaction force
they are equal but in opposite directions - 36what happens when the resultant force is greater than 0?the object is:
*starting or stopping
*speeding up/down
*changing direction - 37which direction does the object accelerate too when the resultant force is greater than 0?the larger one
- 38how do you calculate the resultant force?force 1 - force 2
- 39how do you calculate a force?F = m x a
force = mass x acceleration - 40when does friction occur?when solids are sliding past each other whilst gripping each other
- 41what is friction?the force that opposed movement
- 42when can an object move?when a driving force has been applied
- 43why is a driving force needed to move an object?friction matches the force trying to move an object to a certain point. above that certain point, the action force is greater so the object moves in that direction
- 44what increases the amount of friction on an object?*material
*surface area - 45what is friction in liquids and gases?air resistance (drag)
- 46what is terminal velocity?the fastest an object can fall
- 47when does terminal velocity happen?*when speed > resistance
*speed increases
*so resistance increases
*when speed = resistance
*no more acceleration - 48what causes a slower terminal velocity?bigger area, so more resistance to limit speed
- 49what is breaking distance?the distance it takes from when the breaks are pressed to when the vehicle stops
- 50what affects breaking distance? (6)*speed
*quality of breaks
*mass of vehicle
*quality of tyres
*weather
*road surface - 51what is thinking distance?the distance travelled from seeing an object and reacting to press the breaks
- 52what affects thinking distance? (7)*distractions: phone, music
*bad visibility: weather, cleanliness of car
*unawareness: drugs, alcohol, tired - 53what is stopping distance?thinking distance + breaking distance
- 54how is stopping distance calculated?thinking distance + breaking distance
- 55what causes a long stopping distance?long thinking distance or long braking distance
- 56how is momentum calculated?momentum = mass x velocity
- 57what happens to momentum after a collision?it is always conserved
- 58what has to happen when calculating collision velocity?one of the velocities has to be negative as the objects will be coming towards each other in therefore a different direction
- 59what can change momentum?forces
- 60what is the equation for a force involving momentum?change in momentum
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time - 61how do you calculate change in momentum?mv - mu
(mass x final velocity) - (mass x initial velocity) - 62what is work done?the amount of energy transferred
- 63how is work done calculated?force x distance moved in direction of force
- 64what is power?how much work is done per second
(how much energy transferred in one second) - 65what is the formula for power?work
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time - 66what are the units for: *power *work done*W watts (j / s)
*J joules - 67what is kinetic energy?movement energy
- 68what is momentum?how hard it is to stop a moving object
- 69what happens to the kinetic energy as the force and mass increases?the kinetic energy increases
- 70what is the equation for kinetic energy?1/2mv^2
- 71kinetic energy equals what in brakes?work done (energy transferred)
- 72what is the equation for work done by brakes?F x d
(braking force x distance) - 73what happens to the breaking distance as speed increases?it increases
- 74what happens with the kinetic energy the faster and bigger the mass?it increases
- 75what is gravitational potential energy?energy as a result of height
- 76what happens to energy in falling objects?they convert gravitational potential energy to kinetic energy
- 77what is gravitational field strength on earth?10 N/kg
- 78what is the equation for gravitational potential energy?mass x gravitational field strength x height
- 79what does kinetic energy gained equal to in terms of gravitational potential energy?gpe lost
- 80what is the extension of an elastic object directly proportional to?the force
- 81happens when an elastic object changes shape?work is done. has stored elastic potential energy. kinetic energy is turned into elastic potential energy
- 82what happens when the force is too great on a elastic object?it will not return to its original shape
- 83what is the equation for a force on a elastic object?spring constant (depends on material) (N/m) x extension (m)
- 84what happens in normal car brakes when they are applied?work is done - kinetic energy is converted to sound and heat to stop or slow down the car
- 85what happens when regenerative breaks are applied in cars?*motor put in reverse which slows down wheels
*motor acts as generator converting ke to electrical energy which is stored as chemical energy in the battery - 86why are regenerative brakes useful?the energy is used and not wasted as heat
- 87where are regenerative brakes most commonly found?hybrid/electric cars
- 88what does abs stand for?anti lock breaking system
- 89what does abs do?stops a driver losing control of steering and prevents skidding
- 90how does abs work?it automatically pumps on and off preventing wheels from locking which causes skidding
- 91what happens in car crashes that makes them dangerous?big change in momentum as stops very quickly so very large forces put on passengers
- 92what are cars designed to do in a crash to make them safer?converts the kinetic energy in a way that is safe for passengers. increases the time at which the momentum changes to reduce forces
- 93what are the four safety features cars have to protect passengers in crashes?*crumple zones
*side impact bars
*seatbelts
*airbags - 94what are side impact bars in cars?strong metal bars in doors
- 95what do side impact bars in cars do?direct ke to crumple zones
- 96what are crumple zones?areas at the front and back that change shape on impact
- 97what do crumple zones do in crashes?increase impact time so decrease force on passenger
- 98what do seatbelts do to ensure safety in crashes?*stretch increasing time for passenger to stop
*some of the ke is absorbed by stretch
*reduces impact on chest - 99what do airbags do to keep us safe in crashes?*slow us down gradually
*stop us hitting hard surface at high force - 100what happens to the top speed in more powerful cars?it is higher as more energy is converted from fuel
- 101why can streamline sports cars reach a higher top speed than other cars?streamline reduces air resistance so can reach a higher speed before air resistance = driving force and terminal velocity is reached
- 102when you increase the kinetic energy by a factor of 4, what does the breaking distance increase by?4
- 103what happens to the kinetic energy when you double the mass?it doubles
- 104what happens to the breaking distance when you double the mass and double the kinetic energy?it doubles
- 105what happens to the kinetic when the velocity is doubled?increases by factor of 4 as in the formula v is squared
- 106what happens to the kinetic energy and the breaking distance when the mass is doubled?they double
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- AS - Level Physics (P2) Flashcards on P2.1 - Motion, created by Kelly Jowett on 19/04/2015.
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- Kelly Jowett
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