P-5 Forces Flashcards

1
Q
  • What is a vector quantity
A
  • Have magnitude and associated direction

- Force is a vector quantity

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2
Q

What is a scalar quantity

A
  • Only have magnitude no direction

- Speed, distance

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3
Q

How are vectors represented

A
  • Represented usually by an arrow

- length of arrow represents magnitude and direction shows direction

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4
Q

What are contact forces

A
  • Objects are touching for the force to act

- friction, air resistance, tension and normal contact

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5
Q

What are non-contact forces

A
  • Objects that do not need too be touching for force to act

- e.g magnetic, gravitational and electrostatic

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6
Q

What is a force

A
  • A push or pull that acts on an object due to the interaction with another object
  • Vector
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7
Q

What happens when objects interact

A
  • There is a force produced on both objects

-

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8
Q

What is an interaction pair

A
  • Paire of forces that are equal and opposite and act in two interacting objects
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9
Q

What is weight

A
  • The force acting on an object due to gravitational field around earth
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10
Q

What does weight depends on

A
  • Gravitational field strength
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11
Q

What is the equation for weight

A

Weight = Mass x gravitational field strength

W = m g

weight in newtons

Directly proportional

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12
Q

What are the two effects of gravity

A
  • Makes all things fall towards ground

- Gives things weight

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13
Q
  • What is a centre of mass
A
  • When the weight of an object is considering to act at a single point
  • A point where the whole mass is concentrated
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14
Q

How is weight measured

A
  • Using a calibrated spring balance

- A newtonmeter

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15
Q

What is a resultant force

A
  • ## When a number of forces are acting on an object are replaced by a ginned force that has the same effect as all the force as all the other forces acting together
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16
Q

How do you calculate the resultant forces that act in a straight line

A
  • Add the forces that go in the same direction and subtract that which go in the other direction
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17
Q

What are free body diagrams

A
  • Sizes of arrows show relative magnitudes

- Directions are those which re true

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18
Q

What is work done

A
  • When a force causes an object to move through a distance work is done
  • Force does work on an object when the force causes a displacement of the object
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19
Q
  • What is the equation for work done
A
  • Work done = force time distance

Work done- joules
Force- newtons
- Distance meters

W= F s

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20
Q

What is a joule of work done

A
  • When of force of one newton causes displacment of one meter
  • 1 joule = 1 newton meter
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21
Q
  • What energy is transferred in one work done
A
  • Energy transfers from one store to another

e. g- electric to kinetic

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22
Q

What effect does work done have affect frictional forces

A
  • Frictional forces acting on an object when met with work done cause the temperature to rise
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23
Q

How can scale drawings be used to find resultant forces

A
  • Draw all forces acting on object tip to tail
  • Draw straight line from start of force to end of last one
  • mEasure and angle for direction
24
Q

-why does more than one force have to be acting on an object to stretch compress or bend

A
  • You apply a force

- More than one force needs to acting or else it would just mov in a direction

25
Q
  • What is the difference between elastic deformation and inelastic deformation
A
  • Elastic0 it can go back to original shape ice force removed
  • Inelastic
  • Cannot return to original shape
26
Q

What is the proportion of the extension of an elastic object

A
  • The extension of an elastic object, such as a spring, is directly proportions long as the limit of proportionality is not exceeded
27
Q

What is the equation for force

A

Force = spring constant x extension

Force- F - newtons

  • Spring constant- k- newtons per meter
  • Extension - e- meters
28
Q

What is the relationship between elastic potential and work done

A

§- Unless inelastically deformed , they are equal

29
Q
  • What are the steps in testing link between force and extension
A
  • Measure natural length - on stand
  • Take at eye level - Add mass and allow to come to mess- record length
    _ Repeat until more than 6 results have been taken
    _Plot
    0 when bends- limit of proportinality
30
Q
  • Wheat is the equation for calculating extension
A

Elastic potential= 1/2 Spring constant x exertion 2

E= 1/2KE2

31
Q

What are distance and vector

A
  • Distance is how far an object has moved- scalar

- Displacement is distance and direction0 Scalar - Starting point to finishing point

32
Q

What are speed ad velocity

A
  • Both how fast you are going
  • Speed is just how fast
  • Velocity is speed in given direction
33
Q

What is the equation for distance traveled

A
  • Distance+ speed x time

s=vt

34
Q

What are typical everyday speeds

A
  • Person walking- 1.5m/s
  • Running- 3 m/s
  • Cycling- 6m/s
  • Car-25m/s
  • Train-30m/s
  • Plane250m/s
35
Q
  • What things can effect speed
A
  • Temperature
  • Pressure
  • resistance
36
Q

What is acceleration

A
  • How quickly you are speeding up

- Constant- speeding up air uniform rate

37
Q

What is the equation for measuring equation

A

Acceleration- = Change in velocity // time

a=/\v//t

38
Q

How do you calculate uniform acceleration

A
  • Final velocity2- Initial velocity2 = 2x acceleration distance

v2-u2 = 2as

39
Q
  • What is friction
A
  • Friction always slows things down
  • Acts in opposite direction to movement
  • TO be at steady speed- have to balance
  • Contact force
  • Reduced using lubricant
40
Q
  • What is drag
A
  • Drag is resistance found in fluid- gas or liquid
  • Streamlined stops drag
  • Frictional force sin fluids always increase with speed
41
Q

What is terminal velocity

A
  • When falling object sets off- gravity much than frictional force
  • As speed increases friction builds up
  • Gradually reduced the acceleration until the frictional force is equal to acceleration
  • It will have reached its terminal velocity
42
Q

What does terminal velocity depend on

A
  • Less streamlined objects have lower TV
  • ## Large surface area- low TV
43
Q

What is Newtons first law

A
  • Resultant force is needed to make something , start moving, speed up our slow down
  • Balanced to be moving at constant pace
44
Q

What is Newtons second law

A
  • The larger the resultant force the more the object accelerates- directly proportional
  • Acceleration will also be interlay proportional to mass - Object with larger mass will accelerate less
45
Q

What formula can be used to describe newtons second law

A
  • Resultant force= Acceleration x mass

F= ma

46
Q

What is newtons Third law

A
  • When two object interact the forces they exert on each other are equal and opposite
47
Q

What is inertia

A
  • Inertia is the tendency for motion to remain unchanged
  • ## Until acted upon objects stay at rest
48
Q

What is inertial mass

A
  • Measures how difficult it is to change the velocity of an object
  • M- F//a
    Internal mass is a ratio of force over acceleration
49
Q
  • How do you investigate newtons seined law
A
  • Set up set- Trolley- starting line- card in trolley- Light gate- hook of known mass on the end
  • Weight of hook and any masses with give acceleration
  • Place at starting line and re;are
  • Record acceleration given by light gate
  • Repeated and get average acceleration \
  • Effect of mass- trolley
  • Effect of force- hook
50
Q

What is a stopping distance

A
  • Thinking distance+ Braking distance
51
Q
  • What are thinking and breaking distance-
A
  • Thinking- How far it travels in reaction time

- Breaking- Time it takes to stop under breaking force0 Car - 30mph- 14m - 60mph-55m 70mph-75m

52
Q

What factors effect Stopping distance

A
  • Thinking - Speed- Reaction time

Breaking

  • Speed
  • Weather// Road surface- Wet
  • tyre condition -
  • Break condition
53
Q

What does breaking rely on

A
  • Friction between breaks breaks
  • Faster- more kinetic energy More work needed to stop it
  • Larger breaking force means larger deceleration
54
Q

What is momentum

A
  • Momentum is mainly about how much oomph something has
  • Velocity+ mass
  • Vector
55
Q

What is the equation for momentum

A
  • Momentum = mass x velocity

p=mv

56
Q

What is conservation of momentum

A
  • In a closed system, The total momentum before is the same as after
  • If momentum is zero at start it will end as zero