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Forces- Paper 2 Flashcards

1
Q

1)What is a Vectors?
2) Three examples?
3) what does arrow length and directions show?

A

1) magnitude and direction
2) velocity, displacement, acceleration
3)arrow length=magnitude
direction arrow=direction

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2
Q

1) what is Scalar quantities?
2) what are 3 examples?

A

1)only magnitude
2)speed, distance, mass

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3
Q

1)What are Forces?
2) what are the two types of forces explained with 2 examples each?

A

1)push,pull object caused interacting with something
2)contact or non-contact forces.
.Contact= touching for a force to act friction, air resistance
.Non-contact=not need to be touching force to act
magnetic force, gravity

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4
Q

1)What is an interaction pair?
2) an example?

A

1)pair forces equal and opposite act on two interacting objects.

2).chair exerts a force on ground, ground pushes back at chair same force
.(normal contact force). Equal but opposite forces felt by both chair, ground.

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5
Q

What is Gravitational Force and two effects of it? 3

A

1)Gravity attracts all masses
2)two important effects:
.surface of a planet, makes all things-fall towards the ground.
.It gives everything a weight.

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6
Q

1)Why is Weight and Mass are Not the Same?
3) what does the weight of an object depend on?

A

1)Mass= amount ‘stuff’ in object same anywhere.
Weight= force acting on object due gravity (Gravitational force on it caused by gravitational field)

3)
.stronger= closer you are to mass causing the field
.strength of the gravitational field at the location.

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7
Q

What is weight and mass units?

A

1) Weight=newtons. measured using balance (newtonmeter).
2) Mass is not force. kilograms mass balance

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8
Q

1)What is centre of mass?
2)What is a uniform object?

A

1)point assume whole mass is concentrated acting from a single point
2)same density, throughout=regular shape

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9
Q

1)How are Mass and Weight Directly Proportional?
2) equation for weight?

A

1)Increasing mass, increases its weight. double the mass, the weight doubles too
2)Weight (N)= Mass (KG) x GFS (N/KG)

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10
Q

What is a Free Body Diagrams?

A

describe all forces acting on isolated object.

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11
Q

What is the free body diagram of a Sky diver? 2

A

1)skydiver’s weight acts on him pulling him to ground
2)drag (air resistance) acts on him, opposite direction to his motion.

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12
Q

What is Resultant Force? 4

A

1)number of forces acting at a single point replace by single force (same effect original forces).
2)single force=resultant force.
3)adding when going in the same direction
4)subtracting when going in opposite direction

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13
Q

What happens when an resultant force moves an object through a distance?

A

ENERGY IS TRANSFERRED and WORK IS DONE on the object.

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14
Q

1)Process of making something move with resultant force? 3
3) jJ= ?nm

A

1)
1-force must be applied.
2- force transfers energy to move the object energy is transferred one store to another.

2) 1J = 1 Nm.

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15
Q

What is an example of energy transferred when a resultant force moves an object? 4 (when pushing a block against a surface)

A

1) push something along rough surface work against frictional forces.
2)Energy transferred to the kinetic energy store of the object=moving,
3) some transferred to thermal energy stores due to the friction.
4)causes overall temperature object to increase.

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16
Q

How to use Scale Drawings to Find Resultant Forces? 2

A

1) Draw all forces acting on object, to scale draw straight line from the start first force end of the last force =resultant force.
2) Measure length resultant force on the diagram to find magnitude and angle to find direction of force.

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17
Q

How to draw a scale drawing? 5

A

1) scale drawing of forces acting. (e.g. 1 cm = 1 N)
2) Draw resultant from the tail of the first arrow to the tip of the last arrow.
3) Measure length of resultant with ruler use scale find the force in N.
4) protractor measure direction bearing.
5) bearing an angle measured clockwise from north, 3 digit number

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18
Q

When is an object in Equilibrium? 2

A

1)All forces acting on object combine to give resultant force of zero=equilibrium.
2) scale diagram, tip of the last force you draw should end where the tail of first force you drew begins.

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19
Q

How to find a missing force when an object is in equilibrium? 2

A

1)draw out forces you do know (scale and tip-to-tail), join end of last force to the start of the first force.
2)line is the missing force=measure size and direction. draw last force in right direction. in the opposite direction to how you draw a resultant force

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20
Q

How can you Split a Force into Components? 4

A

1) Not all forces act horizontally or vertically so split into two components right angles each other.
2)Acting together, these components have the same effect as the single force.
3) drawing it on a scale grid. Draw the force to scale, and add horizontal and vertical components along the grid lines.
4)measure them.

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21
Q

What can happen if you apply 2 forces onto something, why do you need two forces? 2

A

1)apply a force to an object cause it to stretch, compress or bend.
2)you need more than one force acting on object (otherwise move in direction applied force, instead changing shape).

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22
Q

1)What is elastic deformity?
2)what energy store happened within elastic deformity?
3)When is work done in this situation? 2

A

1)can go to its original shape and length after the force has been removed.
2)ALL energy is transferred to object’s elastic potential energy store

3)Work is done when force stretches or compresses object= energy transferred
4)transferred to elastic potential energy store of the object.

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23
Q

Inelastically deformed?

A

1)doesn’t return to its original shape and length after force has been removed.

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24
Q

1)What type of Extension Proportional to Force? 2
3)what is spring constant and what does it depend on?

A

1)directly
2)spring constant
depends on material that you are stretching - stiffer spring=greater spring constant.

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25
Q

Why does the extension stop working when too much force is applied, how do you know on a graph? 3

A

1)limit amount of force can apply to object for extension keeps on increasing proportionally.
2)maximum force when the graph curves, extension no longer proportional to force.
3)limit of proportionality.

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26
Q

How to Investigate Link Between Force and Extension? 6

A

1.Secure clamp stand bench using a G-clamp large mass base.
2.Attach spring to the top clamp, ruler to the bottom clamp.
3.Adjust ruler so that vertical, zero level top of the spring.
4.Measure and record unloaded length of the spring.
5.Hang 100 g slotted mass carrier from the spring. Measure record new length spring.
6.add 100g until you have added a total of 1,000 g.

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27
Q

1)Work out Energy Stored drugging spring experiment? (elastic potential energy)
2)What is the elastic potentail energy store of a stretched spring equal to?

A

1)spring is not stretched past its limit proportionality, work done found using:
EPE (j)= 1/2x spring constant (N/M) extension^2 (ET to spring as deformed)

2)equal to the area under a force extension graph up to that point:

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28
Q

1)What is a Moment?
2)what happens when a moment is not pushed at right angles?
3)what is the rule for a moment that is balanced?

A

1)forces cause an object to rotate. turning effect of a force= moment
2)maximum moment=push at right angles to spanner.
Pushing at other angle=smaller distance= smaller moment.
3)total anticlockwise moment= the total clockwise moment about a pivot

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29
Q

What do Levers do?

A

.increase the distance from the pivot at which force is applied.
-less force is needed get the same moment.

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30
Q

What do Gears do?

A

.Transmit Rotational Effects,
1) teeth interlock so that turning one causes another to turn, in opposite direction.
3) transmit the rotational effect of a force from one place to another.
4) Different sized gears used to change the moment of the force=
force transmitted larger gear=bigger moment BC distance to pivot is greater.
5) larger gear will turn slower than the smaller gear.

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31
Q

How is Pressure made?
How does pressure work in fluids?

A

1) particles move around= collide with surfaces + other particles.
2)
Particles=light mass and exert a force on the object they collide
3)
pressure fluid force is exerted normal (right angles)=surface contact with the fluid.

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32
Q

1)density in a Liquids and is it uniform what happens when something is more dense?
2)How does pressure change with depth?

A

1)Density=measure close together particles in substance are
-liquid=density is uniform
-more dense=more particles it has in a certain space=collide pressure is higher.

2)depth liquid increases=
number of particles above point increases.
Weight particles adds pressure felt at point=
liquid pressure increases with depth.

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33
Q

What do Objects in Fluids Experience?

A

1)object submerged in fluid pressure of fluid exerts a force on every direction.
2)pressure more at bottom=resultant force
upthrust= resultant force which acts upwards

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34
Q

What happens when An Object Floats?
What happen when an object sinks?

A

.Upthrust object=object’s weight, then the forces balance, object floats.

1)object’s weight is more than the upthrust=object sinks. (depend on its density.)
.unable to displaces a volume of fluid that is equal to its weight= sink
3)object denser than the fluid it is placed unable to displace enough fluid to equal it’s weight. weight larger than upthrust=sinks.

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35
Q

How do submarines use upthrust?

A

.To sink, large tanks are filled with water to increase weight submarine more than the upthrust. rise surface, the tanks filled compressed air reduce the weight less upthrust

36
Q

What is a Atmosphere?
What is atmospheric pressure how does alitude effect this?

A

1)atmosphere=layer air surrounds Earth. Thin.
2)Atmospheric pressure= air molecules colliding with the surface.
-altitude=increases, atmospheric pressure decreases.
less dense, fewer air molecules collide surface.
-weight of the air above is less

37
Q

Distance is …, Displacement is a …?

A

.Distance=far object has moved. (scalar quantity) distance
.Displacement= (vector quantity) measures distance, direction
=walk 5 m north, then 5 m south, your displacement is 0 m but the distance travelled is 10 m.

38
Q

What is Speed and Velocity?
What is changing velocity?

A

.speed is a scalar
.velocity is a vector:
.Speed how fast you’re going no regard to the direction. Velocity is speed given direction
.changing velocity=happens when object changing direction whilst staying same speed.

39
Q

Typical Everyday Speeds: walking, running, cycling, car, train, plane?

A

.person walking - 1.5 m/s .person running - 3 m/s .person cycling - 6 m/s .car - 25 m/s. .train - - 30 m/s. .plane - 250 m/s

40
Q

How does 3 factors effect the speed of objects?

A

1.temperature
2.atmospheric pressure
3.structures nearby

41
Q

What is Acceleration?

A

.change in velocity in a certain amount of time

42
Q

Uniform Acceleration?

A

.Constant acceleration= Acceleration due to gravity

Final velocity^2(m/s)-initial velocity^2(m/s)= 2x acceleration (m/s^2)distance (m)

43
Q

What can you get from Journeys on Distance-Time Graphs?

A

1)Gradient = speed. (steeper the graph, the faster it’s going.) because speed = distance ÷ time = (change in vertical axis) ÷ (change in horizontal axis).
2) Flat sections=stationary, Straight uphill sections mean it is travelling at a steady speed, Curves represent acceleration or deceleration
3)If the object is changing speed, you can find its speed at a point by finding the gradient of the tangent to the curve at that point.

44
Q

Velocity-Time Graph?

A

How an object’s velocity changes, Gradient = acceleration, since acceleration is change in velocity time.
.curve means changing acceleration=tangent to the curve point to find the acceleration at that point.
1)area under any section of the graph is=distance travelled in that time interval.
2) section under the graph is irregular, it’s easier to find the area by counting the squares under line, multiplying the number by value one square.

45
Q

Distance graph?

A
46
Q

Velocity graph?

A
47
Q

1)What happens when a there is no propelling force?
2)What does.Friction do, how does it work and when do you get it?
3)How to travel at a steady speed?

A

1)slow down stop because of friction

2)Friction always acts opposite direction to movement.
.You get friction between two surfaces in contact, or when an object passes through a fluid (drag).

3)travel steady speed=driving force needs balance the frictional forces

48
Q

1-what is drag?
2-Why does Drag Increases as Speed Increases?
3-How can you reduce drag?

A

1-Drag=resistance you get in a fluid Air resistance is a type of drag
2-Frictional forces from fluids always increase with speed. more air molecules are striking the leading surface of the object per second as its speed increases.
3-reducing drag=keeping the shape of the object streamlined.

49
Q

How do parachutes work?

A

.want as much drag as they can get

50
Q

Process Objects Falling Through Fluids Reaching terminal velocity?

A

1)falling object first sets off, force of gravity more than frictional force slowing it down=accelerates.
2) speed increases the friction builds up. gradually reduces acceleration until eventually frictional force=equal accelerating force ( resultant force is zero).
Reached maximum speed or terminal velocity= fall at a steady speed.

51
Q

Why does Terminal Velocity Depends on Shape and Area?

A

1-air resistance causes things to fall at different speeds, terminal velocity object determined by drag in comparison to its weight.
2-The frictional force depends on its shape and area.

52
Q

How does a skydiver manipulate his shape? 3

A

1-Without his parachute open=quite a small area and force of pulling him down.
2-reaches a terminal velocity of 120 mph.
3-parachute open, much more air resistance and still only same force pulling him down.
terminal velocity comes down 15 mph, which is a safe speed.

53
Q

Newton’s First Law?

A

.resultant force needed to make something start moving, speed up or slow down;
.If the resultant force on a stationary object is zero, the object will remain stationary.
If the resultant force on a moving object is zero, it’ll carry on moving at the same velocity.

54
Q

Newton’s second law?
acceleration
what is it directly proportional to and inversely

A

1)larger the resultant force acting on an object= more the object accelerates= Directly Proportional.
2) Acceleration inversely proportional mass object .object larger mass will accelerate less one with smaller mass.

55
Q

What is Inertia?

A

.tendency to continue same state of motion=inertia. (Newton’s First Law)
1)An object’s inertial mass measures how difficult it is to change the velocity of an object.
2)Inertial mass can be found using Newton’s Second Law=
mass (kg) = Resultant force (n) ÷ acceleration (m/s^2)

56
Q

Newton’s Third Law?

A

When two objects interact, the forces they exert on each other are equal and opposite.
1)you push something, the trolley will push back against you, just as hard, soon as you stop pushing, so does object.

57
Q

Example of Newton’s third law in a equilibrium situation?

A

-man pushing against a wall. Wall pushes the man=normal contact force acting back on him.
-two forces same size. Pushes back with equal force.

58
Q

Example of objects that isn’t Newton’s third law: book and a ground why?

A

.book resting on the ground is in equilibrium. weight of the book=normal contact force.
.NOT Newton’s Third Law because the two forces are different types, and both acting on the book.

59
Q

Method to Investigate how Force Affect Acceleration?

A
  1. Position an air track on a bench with a bench pulley at one end and two light gates above the track. Cut an card to a known length ( 10 cm) and attach it to an air track glider.
  2. Connect the glider to a hanging mass by a string the length of the air track passing over the bench pulley.
  3. Set the data logging software to calculate acceleration.
  4. Add 5 × 20 g slotted masses (1 N of force) to the end of the string.
  5. Release the glider, then record the weight and acceleration.
  6. Repeat steps 4 and 5 two more times, and calculate a mean value for the acceleration. Reducing mass on the pulley by 20g need to put them on the trolley so mass is constant
60
Q

Method of investigating mass and acceleration?

A
  1. Position an air track on a bench with a bench pulley at one end and two light gates above the track. Cut an interrupt card to a known length ( 10 cm) and attach it to an air track glider.
  2. Connect the glider to a hanging mass by a string the length of the air track passing over the bench pulley.
  3. Set the data logging software to calculate acceleration.
  4. use 100 g of force for every run, add increasing numbers of slotted masses to glider by 20gs.
  5. Record total mass of the glider and hanging masses combined.
61
Q

A Factor Affect Your Total Stopping Distance?

A

.emergency a driver may perform an emergency stop. longer it takes to perform an emergency stop, higher risk of crashing

62
Q

How is stopping distance found?

A

Stopping Distance = Thinking Distance + Braking Distance
.longer your stopping distance, the more space you need to leave in front in order to stop safely.

63
Q

THINKING DISTANCE?

A

.how far the car travels during the driver’s reaction time

64
Q

BRAKING DISTANCE?

A

.distance taken to stop under the braking force

65
Q

Thinking distance is affected by?

A

1)SPEED - faster going further travel time you take to react.
2) REACTION TIME - longer your reaction time, longer your thinking distance.

66
Q

Braking distance/stopping distance is affected by? 4

A

1) SPEED - faster a vehicle travels, the longer it takes to stop.
2) WEATHER or ROAD SURFACE - wet or icy, leaves or oil on the road, less grip (less friction) vehicle’s tyres.
3) CONDITION TYRES - tyres of a vehicle are bald (No tread left) cannot get rid of water in wet conditions=skidding
4)quality of BRAKES are - worn or faulty, apply as much force.

67
Q

Why does Braking Relies on Friction Between the Brakes and Wheels?

A

1) brake pedal is pushed, brake pads pressed onto wheels= contact causes friction, energy transfer= KE stores of wheels
to thermal energy stores of the brakes. temperature. Increases
2) faster a vehicle is going, more kinetic energy stores, more energy to transfer to stop=greater braking force is needed.
3)larger braking force means a larger deceleration=dangerous because brakes to overheat or could cause the vehicle to skid.

68
Q

How does Reaction Times Vary From Person to Person how is it affected by other factors?

A

.reaction time is different
.affected by tiredness, drugs or alcohol. Distractions

69
Q

Digital measure reaction time?

A

.One way of measuring reaction times is to use a computer-based test (e.g. clicking a mouse screen changes colour).

70
Q

Method Measure Reaction Times with the Ruler Drop Test? 6

A

1)arm resting edge of a table someone else hold a ruler hangs between your thumb and forefinger, lined up zero.
2)Without warning, holding ruler drop it. Close thumb finger catch ruler quickly as possible.
3) measurement ruler point caught far ruler dropped time it takes react.
4)longer the distance=longer reaction time.
5)calculate long ruler falls (reaction time) because acceleration due gravity constant (9.8 m/s°).
6) repeats and calculate average reaction time.

71
Q

How to avoid accidents?

A

1)stopping distance for whatever speed they’re going at from car.
2)Speed limits are really important because speed affects the stopping distance so much.

72
Q

How Speed Affects Braking Distance More Than Thinking Distance?

A

-car speeds up, thinking distance increases same rate as speed.=graph linear
1) thinking time stays constant
3)Braking distance=increases faster you speed up. -work done to stop the car is equal kinetic energy store speed doubles,
- (2^2), energy transferred to stop the car increases- braking distance incraeses

73
Q

What is momentum?
How do you know if something has a larger momentum?

A

.Momentum = Mass × Velocity
-Force a moving object has.
1) greater the mass of an object, greater its velocity=more momentum the object has.
2) Momentum is a vector quantity - size and direction.

74
Q

conservation of momentum and an example?

A

1)closed system, total momentum before an event same as after the event.
2)momentum before an event is zero, then the momentum after will also be zero.
Momentum (kg m/s)= Mass (kg) x velocity (m/s)

75
Q

How can Conservation of Momentum be used to Calculate Velocities or Masses?

A

.Negative= opposite direction
.Momentum (kg m/s)= Mass (kg) x velocity (m/s) (rearrange)

76
Q

How do Forces Cause a Change in Momentum?
What does larger force cause?

A

1)non-zero resultant force acts moving object=velocity change=change in momentum.
2) the force causes the rate of change of momentum.
(larger force=faster change of momentum.)

77
Q

Momentum in a car crash and how is safety involved?2

A

-someone’s momentum changes very quickly, forces on the body will be very large= injury.
=slow people down over a longer time in crash - longer takes change in momentum=smaller rate change momentum=smaller the force.= safer

78
Q

Safety features (3) of cars?

A

1)Crumple zones crumple on impact=increasing time taken for the car to stop.
2)Seat belts stretch slightly=increasing the time taken for the wearer to stop.
3)Air bags inflate before you hit the dashboard of a car (compressing air inside slows you down gradually)

79
Q

Safety feature Bike helmets? 2

A

-crushable layer foam=lengthen time taken for your head to stop in a crash
.reduces the impact on your brain.

80
Q

Safety feature Crash mats? 2

A

.cushioned flooring increase the time taken for you to stop if you fall on them.
.soft, compressible materials.

81
Q

Voltmeters?

A

Connecting parallel across a component to test wires. Red is positive and black is negative. (PD)

82
Q

What is a ammeter?

A

Connecting series with component to test current

83
Q

Multimeters?

A

Measure potential difference and current
Dial turn to relevant section

84
Q

What do you light gates measure?

A

Speed and acceleration

85
Q

How do light gates measure? 4

A
  1. Beam light on one side of the gate to detect the other side when something passes through beam measures how long.
  2. find speed connect the light gate to a computer to measure length of object and input to software
  3. Acceleration object interrupt signal twice in a short period of time.
  4. gate measures speed each section, to calculate acceleration
86
Q

Three stages as an object falls through a fluid? (skydiver)

A

1,skydiver accelerates as they begin to fall
2.speeds up the air resistance force increases
3.terminal velocity the air resistance force and weight are equal so speed is constant
4.parachute opens which increases the air resistance and slows the skydiver
5.skydiver continues to slow down until the new air resistance force and weight are equal again (new terminal velocity)

Physics (12 decks)

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