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Flashcards

Forces- Physics Topic 5

Jessie Howes Physics Year 10 English 87 cards

Cards in this deck (87)

  1. 1What is a vector quantity?A vector quantity has a magnitude and a direction
  2. 2Give 3 examples of vector quantitiesForce
    Velocity
    Displacement
    Acceleration
    Momentum
  3. 3What's a scalar quantityA scalar quantity has a magnitude but no direction
  4. 4Name 3 examples of scalar quantitiesSpeed
    Distance
    Mass
    Temperature
    Time
  5. 5How are vectors usually represented?With arrows- the size represents magnitude and the direction of the arrow shows the direction of the quantity
  6. 6What's a force?A push or pull on an object caused by interacting with something
  7. 7What's a contact force?When two objects have to be touching in order for a force to act
  8. 8Give 3 examples of contact forceFriction
    Air Resistance
    Tension in ropes
    Normal Contact force
  9. 9What's a non contact forceWhen the objects don't have to be touching for the force to act
  10. 10Give 3 examples of non contact forceMagnetic Force
    Gravitational Force
    Electrostatic Force
  11. 11What's an interaction pair?A pair of forces that are equal and opposite and act on two interacting objects.
    i.e a chair pushes on the ground (gravity), but the ground pushes on the chair (supporting)
  12. 12What is gravitational force?The force of attraction between masses (happens with all masses, but only noticeable when one is really big - like a planet)
  13. 13What are the two important effects of gravity?1. All things fall towards the ground on the surface of a planet
    2.Gives everything a weight
  14. 14What is mass?The amount of 'stuff' in an object. It doesn't change depending on the strength of gravity
  15. 15What is weight?The force acting on an object due to gravity (the pull of the gravitational force on an object)
  16. 16What does the gravitational field strength vary on?Location- the closer you are, the stronger it is, meaning weight changes with location
  17. 17What is weight measured in?Newtons (N)
  18. 18What is the centre of mass?The point where the force acts from (it will be at the centre of a uniform object)
  19. 19How is weight measured?With a calibrated spring balance or a newtonmeter
  20. 20What is the equation for weight?Weight (N) = mass (kg) x Gravitational Field Strength (N/kg)
  21. 21True or false: Weight is indirectly proportional to weightFalse - they're directly proportional
  22. 22What does a free body diagram showThe forces acting on an object, but not the forces the object is exerting on the rest of the world
  23. 23What do the arrow sizes in a free body diagram represent?The magnitude and direction of the force acting on the object
  24. 24What's a resultant force?The total force acting on an object (i.e a skydiver with an upward force of 2N and a downwards force of 10N would have a resultant force of 8N accelerating downwards)
  25. 25What happens when a force moves an object through a distance?Energy is transferred and work is done
  26. 26What energy types are being transferred when a object is being dragged along a carpet (frictional force)Object moving - some transferred to kinetic energy stores
    Friction - some transferred to thermal energy stores, so object heats up
  27. 27Whats the equation for finding out how much work has been done?Work done (J) = Force (N) x distance (m)
  28. 28How do you convert Joules into Newtonmeters?1J=1Nm
    One Joule of work is done when a force of one newton moves an object a distance of one meter.
  29. 29How do you use a scale drawing to find the total resultant force?1. Draw the vertical and horizontal forces at a 90 degree angle using a sensible scale
    2.Draw a line from the ends of the two forces, forming a right angle triangle
    3. Measure the length and use the scale to find the force
    4. Use a protractor to measure the direction as a bearing
  30. 30What's the resultant force of an object in equilibrium?0N
  31. 31What does a scale drawing of an object in equilibrium look like?All of the force lines join together - no need for a resultant force line
  32. 32How do you resolve a force (split it into components)?Draw the force line to scale, then draw the horizontal and vertical components from the end of the line, which you can just measure.
  33. 33What does elastically deformed mean?The object returns to its original shape after being stretched/ bent/ compressed
  34. 34What does being inelastically deformed mean?Doesn't return to it's original shape after being compressed/stretched/bent
  35. 35Where does energy transfer to when an object changes shape?Elastic potential energy store
  36. 36Extension is directly proportional to what?Force
  37. 37What's the equation of the force acting on a spring while being stretched?Force (N) = Spring constant (N/m) x Extension (m)
  38. 38What does the spring constant depend on?The material being stretched - the stiffer the spring, the greater the spring constant
  39. 39What's the equation for the force acting on a spring while being compressed?Force (N) = Spring constant (N/m) x difference between natural and compressed lengths (m)
  40. 40What's the limit of proportionality?The point where extension is no longer directly proportional to force
  41. 41What's the equation for the work done in stretching/compressing a spring?Elastic Potential Energy (J) = 1/2 x Spring constant (N/m) x extention^2 (m)
  42. 42How do you find the spring constant from an extension-force graph?It's equal to the gradient of the line
  43. 43What's a moment of a force?The turning point (object rotates)
  44. 44What's the equation for a moment of a force?Moment of a force (Nm) = Force (N) x distance (m)
    Distance = perpendicular distance from pivot to line of action of the force
  45. 45Why won't a balanced object rotate?the anticlockwise moment = the clockwise moment
    You can use this to calculate a missing force or distance
  46. 46Why do levers make it easier to do work?Increases the distance from the pivot. M=Fd, so less force is needed to get the same moment
  47. 47What do gears do?Transmit rotational effect of a force from one place to another
  48. 48What do different sized gears change?The moment of the force - a larger gear has a greater moment as there's a bigger distance from the pivot
  49. 49What is pressure?The force per unit area
  50. 50What is the pressure of a fluid?The force exerted at right angles to any surface in contact with the fluid
  51. 51What's the equation for pressure?Pressure (Pa) = Force (N) / Area of surface (m^2)
  52. 52Why is pressure higher when a liquid is more dense?There's more particles to exert a force on the surfaces in contact with the liquid.
  53. 53What's the equation for calculating pressure at a certain depth?Pressure (Pa)= Depth (m) x density (kg/m^3) x gravitational field strength
    (Normally write answer in standard form)
  54. 54Why do objects in fluids experience upthrust?When an object in in fluid, the pressure of the fluid exerts a force in every direction.
    Pressure increases with depth, so there's more force acting on the bottom of the object than the top
    Therefore there's an upward resultant force called upthrust.
  55. 55What is upthrust equal to?The weight of the fluid that has been displaced by the object
  56. 56Why do objects float?When the upthrust on an object is equal to the object's weight, the force balances and the object floats
  57. 57When does an object sink?When the object's weight is more than the upthrust
  58. 58Explain how density links to whether an object will float or sinkAn object that's less dense than the liquid weighs less than the equivalent volume of fluid. It displaces a volume of weight equal to it's weight before it's fully submerged
    An object that's more dense than the fluid is unable to displace enough fluid to equal it's weight so it sinks, as the weight is larger than the upthrust
  59. 59Why does atmospheric pressure decrease when altitude increases?Atmosphere is less dense - there're fewer air molecules to collide with the surface.
    Also, there are less air molecules above the surface so the weight of the air above decreases with altitude
  60. 60What is distance?How far an object moves
  61. 61What is displacement?Measures distance and direction in a straight line from the starting point to the finishing point. Direction could be relative to a point (i.e. towards the building) or as a bearing
  62. 62What is speed?A measure of how fast an object is going
  63. 63What is velocity?A measure of how fast an object is going in a given direction (30 mph north or as a bearing)
  64. 64How can an object have a constant speed but a changing velocity?It changes direction while staying at the same speed
  65. 65Whats the equation for speed?Speed = Velocity x Time
  66. 66What's the equation for distance travelledDistance = Speed (m/s) x time (s)
  67. 67What's the average speed of a person walking?1.5 m/s
  68. 68What's the average speed of a person running?3 m/s
  69. 69What's the average speed of a person cycling?6 m/s
  70. 70What's the typical speed for a car?25 m/s
  71. 71What's the typical speed of a train?55 m/s
  72. 72What's the typical speed of a plane?250 m/s
  73. 73What are 3 factors effecting the speed at which a person can walk, run or cycle?Age
    Fitness
    Distance Traveled
    Terrain
  74. 74Name 3 factors affecting wind speedTemperature
    Atmospheric Pressure
    Large Structures and buildings nearby
  75. 75What is acceleration?How quickly an object is speeding up
  76. 76What's the formula for finding an average acceleration?Acceleration (m/s^2) = Change in velocity (m/s) / time (s)
  77. 77What is deceleration?How quickly an object slows down - it has a negative change in velocity, and the average acceleration will be a negative value
  78. 78EXAM QUESTION NOTEThe exam board could ask for acceleration, but using estimates, so they don't give you any values
  79. 79What is uniform acceleration?Constant acceleration - accelerating at a constant rate
  80. 80What's the equation for finding uniform acceleration?Final Velocity^2 (m/s) - Initial velocity^2 (m/s) = 2 x acceleration (m/s^2) x distance (m)
  81. 81How do you calculate speed from a distance time graph?Speed = Gradient
    (Distance/ Time)
  82. 82How do you find the acceleration from a velocity time graph?Acceleration = Gradient
  83. 83Why will a moving object with no force propelling it, slow down or stop?Friction
  84. 84How does friction act upon an object?In the opposite direction to movement
  85. 85What needs to happen in order to travel at a constant speed?The driving force needs to be balanced with the frictional forces
  86. 86When do you get friction?Two surfaces in contact
    Passing through a fluid (drag)
  87. 87—

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Flash cards for AQA 9-1 GCSE Physics Topic 5
Created by
Jessie Howes
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