Forces Flashcards

1
Q

what is a scalar?

A

quantity with magnitude only

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2
Q

what is a vector?

A

quantity with both magnitude and direction

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3
Q

what is distance?

A

how far an object moves (m) - scalar

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4
Q

what is displacement?

A

distance an object moves, measured in straight line from start point to end point and in the direction of that line - vector

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5
Q

what is speed?

A

distance an object moves per second (m/s) - scalar

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6
Q

what is velocity?

A

speed in a given direction (m/s)- vector

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7
Q

what is the resultant force?

A

overall force acting on an object

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8
Q

the steeper a distance time graph; ….

A

the faster the motion

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9
Q

what does a horizontal line on a distance time graph mean?

A

the object is stationary

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10
Q

what does a a curved line on a distance time graph mean?

A

the object is accelerating or decelerating

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11
Q

the steeper a velocity time graph;…

A

the greater the acceleration

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12
Q

what does a horizontal line on a velocity time graph mean?

A

the object is at a constant velocity

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13
Q

what does a a downward sloping line on a velocity time graph mean?

A

the object is decelerating

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14
Q

what is the gradient on a velocity time graph?

A

acceleration

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15
Q

what is the area under the line on a velocity time graph?

A

displacement

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16
Q

how do you calculate velocity?

A

displacement / time.

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17
Q

all objects with ____ produce a gravitational field.

A

mass

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18
Q

what gives an object a greater gravitational field?

A

a greater mass

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19
Q

what is weight?

A

force acting on an object due to gravity (N)

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20
Q

what happens When a force acts on an object?

A

the object may change shape by bending, stretching or compressing - or a combination of all three shape changes.

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21
Q

what is A change in shape called?

A

deformation

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22
Q

what happens to elastic deformation when the force is removed?

A

it is reversed

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23
Q

what happens to inelastic deformation when the force is removed?

A

it is not fully reversed when the force is removed - there is a permanent change in shape

24
Q

what is hooke’s law?

A

force (N)= spring constant (N/m) × extension (m)

25
Q

what is the spring constant?

A

a measure of the stiffness of a spring up to its limit of proportionality.

26
Q

what is the limit of proportionality?

A

the point beyond which Hooke’s law is no longer true when stretching a material

27
Q

what is the elastic limit of a material?

A

the furthest point it can be stretched or deformed while being able to return to its previous shape.

28
Q

when does a moment occur?

A

when a force is applied at a distance from a pivot

29
Q

how do you calculate a moment?

A

force x distance

30
Q

for an object at equilibrium, the sum of the clockwise moments = ?

A

the sum of the anticlockwise moments

31
Q

what is the centre of mass?

A

the point at which the mass can be thought to be concentrated - the point from which the weight of an object acts

32
Q

if an object is stable, where will the line of action fall?

A

inside the base

33
Q

do big gears have a bigger or smaller moment?

A

bigger - as the distance to the pivot is greater

34
Q

do big gears rotate at higher or lower speeds than small gears?

A

lower

35
Q

what happens in low gear?

A

a small gear turns a larger gear which gives a low speed and high turning effort

36
Q

what happens in high gear?

A

a large gear turns a smaller gear which gives a high speed and low turning effort

37
Q

what is a fluid?

A

anything which can flow

38
Q

how do you calculate pressure?

A

force / area

39
Q

what is pressure measured in?

A

pascals, Pa, or N/m^2

40
Q

how do you calculate pressure due to a column of liquid ?

A

density of liquid x height of column x strength of gravity

41
Q

what is upthrust?

A

the upwards force which acts on an object in any fluid, which occurs because the pressure at the bottom of the object is greater than the pressure at the top; if the upthrust is bigger than the weight, the object will rise

42
Q

what is stopping distance?

A

thinking distance + braking distance

43
Q

what are some factors that affect thinking distance?

A
  • age
  • alcohol
  • drugs
  • distractions
  • speed
  • tiredness
44
Q

what are some factors that affect braking distance?

A
  • mass of car
  • speed
  • road surface
  • condition of brakes
45
Q

what is braking distance proportional to?

A

speed of vehicle^2

46
Q

what is newton’s first law?

A

objects stay at rest or move with constant velocity unless acted upon by a resultant force

47
Q

what is newton’s second law?

A

f = m a

48
Q

what is newton’s third law?

A

when two objects interact, they exert an equal and opposite force on each other

49
Q

what is acceleration?

A

change in velocity of an object over time (m/s^2)

50
Q

what is inertia?

A

tendency of objects to continue in uniform motion

51
Q

what happens at terminal velocity?

A

the object moves at a steady speed in a constant direction because the resultant force acting on it is zero.

52
Q

what are the three stages as an object falls through a fluid?

A
  • at the start, the object accelerates downwards due to the force of gravity
  • as the object’s speed increases, frictional forces such as air resistance or drag increase
  • at terminal velocity, the weight of the object due to gravity is balanced by the frictional forces, and the resultant force is zero
53
Q

how do you calculate momentum?

A

mass (kg) x velocity (m/s)

54
Q

what is the principle of conservation of momentum?

A

in a closed system, the total momentum before the event is equal to the total momentum after. if momentum is not conserved in an event such as a collisions it is because external forces are acting on the objects

55
Q
A