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Physics > Forces P1 > Flashcards

Forces P1 Flashcards

1
Q

Types of forces

A
  • non contact (magnetic force)
  • contact (reaction force)
  • electrostatic force
  • friction
  • air resistance
  • gravitational force
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2
Q

What do opposite charges and like charges do

A
  • opposites attract

- like repel

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3
Q

What is Newton’s first law of motion

A
  • if the resultant force acting on a stationary object is zero then the object will remain stationary
  • if the resultant forcing acting on a MOVING object is zero, then the object will continue moving in the same direction at the same speed (with the same velocity)

(An object will stay stationary or continue moving at the same speed and direction, unless a resultant force is applied)

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4
Q

Work done equation

A

work done (j) = force (n) x distance (d)

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5
Q

What are the types of energy transfer

A
  • mechanical work (a force moving an object through a distance)
  • electrical work (charges moving due to a pd)
  • heating (due to temp difference caused electrically or by chemical reaction
  • radiation (energy transferred as a wave like light (radiation) and infrared (radiation) which are emitted from the sun)
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6
Q

What will happen if we take away the forces acting on elastic materials

A
  • they will always return to their original length or shape
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7
Q

What is elastic deformation

A

When the elastic changes shape

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8
Q

What is the difference between elastic and in elastic deformation

A
  • elastic deformation is reversed when the force is removed

- inelastic deformation is not fully reversed when the force is removed (there is a permanent change in shape)

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9
Q

What do you have to do in order to change an objects shape or length

A

Apply more than one force

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10
Q

What would happen if you only applied one force to a stationary object

A

The forces are no longer balanced, so the object would simply move rather than change shape or length

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11
Q

Example of inelastic materials

A
  • certain polymers
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12
Q

What is the calculation for the force needed to stretch an elastic object OR compression when an elastic object is squeezed

A

Force (n) = spring constant (n/m) x extension (m) OR compression (m)

F = k x e

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13
Q

What is only true if an object is not inelastically deformed

A
  • when stretching or compressing an elastic object, we’re using a force to do work (elastic potential energy is stored in object)
  • work done is equal to the elastic potential energy
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14
Q

What are contact forces and non contact forces

A
  • contact (physically touching)

- non contact (physically separated)

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15
Q

What are examples of a contact force

A
  • Tension in a rope
  • friction
  • air resistance
  • normal contact force (can only happen if the two objects are in direct contact)
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16
Q

Examples of non contact force

A
  • gravitational force
  • electrostatic force (the force between two charged objects)
  • magnetic force
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17
Q

What do objects with opposite charges experience

A

An electrostatic force of attraction

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18
Q

What’s the difference between velocity and speed

A
  • velocity has a direction and so is a vector quantity
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19
Q

What is a scalar quantity

A

When something has magnitude but no direction

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20
Q

What is the speed calculation

A

speed (m/s) = distance (m) divided by time (s)

In triangle distance is at the top

21
Q

What does displacement tell us

A
  • The distance that an object moves in a straight line from the start point to the finish point
  • it is a vector quantity as it includes the direction and magnitude
22
Q

What must displacement include

A

The direction of that straight line

23
Q

What is speed

A

A scalar quantity as it does not involve direction

24
Q

What are the typical speeds

A
  • normal walking speed = 1.5m/s
  • running speed= 3m/s
  • cycling speed= 6m/s
  • car on a main road= 13m/s
  • fast train in the uk= 50m/s
  • cruising aeroplane= 250m/s
25
Q

What does speed depend on

A
  • age
  • fitness (whether they were fitter or unfit)
  • the terrain (uphill would be slower and flatter would be faster)
  • distance travelled
26
Q

What is the typical value of speed of sound in air

A
  • 330m/s but the speed in air can vary depending on the weather (speed travels faster on warmer days rather than colder days)
27
Q

Speed of a moving object…

A

The speed of a moving object is rarely constant

28
Q

Distance travelled by an object moving at a constant speed (average speed) calculation

A

Distance (m) = speed (m/s) x time (s)

29
Q

What is velocity

A
  • A vector quantity
  • it includes both magnitude and direction
  • it’s an objects speed in any direction
30
Q

How is velocity calculated

A

The same way as speed, just state the direction they are going in

31
Q

What happens to the velocity of an object if it’s moving at a constant speed in a circle

A

The velocity is constantly changing even though it’s speed stays constant

32
Q

How can an object moving along a straight line be presented in terms of distance

A

A distance time graph

33
Q

How do you work out the speed on a distance time graph

A

Using the gradient which is,

distance travelled divided by time taken

34
Q

What does an upwards curve on a distance time graph mean

A

The object is constantly increasing in speed (accelerating)

35
Q

What does the acceleration tell us

A

The change in it’s velocity over a given time

36
Q

Calculation for acceleration

A

Change in velocity (m/s)
————————————- = acceleration (m/s2)
Time (s)

Change in velocity is at the top of triangle

37
Q

What do you do if the velocity in a question reduces (acceleration)

A

Take it away, if it was reduces to zero from 6 you would do 0-6=-6

38
Q

What do you have if you end up with a negative number in a question (acceleration)

A
  • the object is slowing down and decelerating

- deceleration

39
Q

What does the gradient of a velocity time graph tell us

A

The acceleration of the object

40
Q

What does it mean if the line is horizontal on a velocity time graph

A

The object is travelling at a constant speed

41
Q

What is the calculation for acceleration on a velocity time graph

A 
Final velocity (m/s) - initial velocity (m/s)
——————————————————-
                         Time (s) 
                               =
         Acceleration (m/s squared)
42
Q

What does the total area under the graph tell us and how do we find it (velocity time graph)

A
  • The displacement (the distance travelled in a specific direction)
  • when we see constant acceleration or deceleration, we divide the graph into shapes and calculate their total area then add them together
43
Q

How to calculate the total area of a velocity time graph when the deceleration and acceleration are not constant

A
  • Count the number of squares complete or almost complete
  • estimate the number of squares remaining
  • add the numbers together
  • mulitiply the number of squares by the total area of one square
44
Q

What is air resistance

A

An upward force of friction

45
Q

What is it called when an object stops accelerating and moves at a constant velocity

A

Terminal velocity

46
Q

What will a greater force of friction result in (in terms of acceleration)

A

A lower terminal velocity

47
Q

What is it called when something is moving at a constant speed and there must be an equal force acting to the right

A
  • The resistive forces

- they include friction with the air and friction with the road (in terms of car)

48
Q

What does a resultant force cause

A

An objects speed to change or an objects direction

Physics (5 decks)

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