Topic 1 - Motion, Forces and Concervation of energy Flashcards

1
Q

Whats the difference between weight and mass?

A

mass has a magnitude but no direction making it scalar whereas weigh is a vector and it has a direction and a size

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2
Q

Whats the difference between displacement and distance

A

Displacement is vector

Distance is scalar

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3
Q

Whats the difference between Velocity and speed

A

velocity is a vector speed is scalar

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4
Q

What does accelerating mean

A

How quickly you are speeding up so change in velocity in amount of time

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5
Q

What does momentum mean

A

proportion of mass x velocity

it is how much power “oomph” something has to move

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6
Q

How can speed be measured in a lab

A

How long it takes for someone to walk a set distance

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7
Q

What is the formula relating acceleration

A

Change in velocity / time

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8
Q

Whats the formula relating acceleration, velocity and distance

A

velocity^2 - initial velocity^2 = 2 x acceleration x distance

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9
Q

what is the acceleration in free fall

A

10m/s^2

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10
Q

What is a resultant force

A

overall force acting on an object in a certain direction

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11
Q

what is the effect of balanced forces on moving and stationary objects

A

The forces are not balanced on an object which is accelerating but are when an object is stationary

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12
Q

What is the effect of a non-zero resultant force on moving or stationary object

A

-non- zero forces always produce an acceleration or deceleration in the direction of the force
(this can be in any direction , stopping, starting, slowing or speeding)

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13
Q

What is circular motion at a constant speed

A

Circular motion causes a constantly changing velocity and therefore an acceleration

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14
Q

What force is needed to keep an object moving in a circular path

A

A centripetal force

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15
Q

Can you name an example of an object moving in circular motion with a constantly changing velocity

A

A planet ii orbit

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16
Q

What is the difference between weight and mass

A

mass is the amount of stuff in an object and is a scalar quanity
weight is a vector and is the force due to gravity

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17
Q

What factors determine an objects weight

A

gravitational field strength and force surrounding an object

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18
Q

what equation relates Gravitational Potential energy

A

mass x GFS x change in height

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19
Q

what equation is used to find weight

A

mass x GFS

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20
Q

How can weight be measured

A

Newton meter/ calibrated spring balance

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21
Q

what is an acceleration

A

a changing velocity

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22
Q

What factors effect acceleration

A

change in speed / time
&
Resultant force/ mass

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23
Q

What is the equation relating the factors in acceleration with resultant force

A

resultant force / mass

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24
Q

What does inertial mass mean

A

Ratio of force over acceleration, determines how difficult it is to change the velocity of an object

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25
Q

What does newtons 3rd law state

A

when two objects interact the forces they exert on each other are equal and opposite

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26
Q

What does newtons 2nd law state

A

Acceleration is proportional to the resultant force

Force = mass x acceleration

27
Q

what does newtons 1st law state

A

an object will continue moving at a constant velocity unless acted on by an unbalanced force

28
Q

What is an equilibrium situation

A

when forces acting on each other are equal

29
Q

what are action reaction pairs?

examples?

A

-when an object pushes on another object causing an action force
-they feel an equal and opposite force in opposite directions and so accelerate further away from each other
Eg) skaters pushing against each other

30
Q

What factors effect momentum

A

mass x velocity

31
Q

What is the idea of conservation of momentum

A

total momentum before = total momentum after

32
Q

Name some examples of momentum in collisions

with car and wall

A

If a car hits a wall and the wall has momentum of 0 and the car is moving with a velocity then when the car hits a wall it causes the wall to now have a momentum

33
Q

How can we measure human reaction times

A

On a computer based test or Ruler drop test

-record distance ruler dropped and time to work out speed

34
Q

What is the typical human reaction time

A

0.2 to 0.6 seconds

35
Q

whats the link between stopping, thinking and braking distances

A

Thinking distance is the drivers reaction time
Braking distance is distance when brakes are applied

Thinking + Braking = Stopping Distance

36
Q

What factors effect stopping distance

A

tiredness
drugs or alcohol
distractions
friction between tires and road eg) icy or wet

37
Q

What does work done mean

A

measure of energy transfer when a force moves an object through a distance.

38
Q

Explain work done with a cars kinetic energy store

A

energy in a cars kinetic energy store equals the work done by the brakes.

39
Q

What is the work done formula

A

force x distance

40
Q

What factors effect kinetic energy of a moving object

A

The mass and velocity

41
Q

How do you calculate kinetic energy

A

1/2 x mass x velocity^2

42
Q

What does a large deceleration mean

A

having a larger force slow an object down in a shorter amount of time.

43
Q

How can large accelerations be prevented

A

The force can be lowered by slowing an object down over a longer period

44
Q

What are the dangers of large decelerations

A

They cause serious injuries because it requires a large force

45
Q

How can we decrease impacts of large decelerations in cars

A
  • crumple zones - increase stopping time
  • airbags - slow impact
  • seatbelts - stretch slightly
46
Q

What forces are typically involved in road collisions

A

-Brakes do work on wheels which transfers energy
from kinetic energy store to thermal energy store
-Force causes brakes to overheat due to large deceleration so might not work properly

47
Q

what does conservation of energy mean

A

That energy is never created or destroyed but transferred between stores

48
Q

Name 4 ways energy can be transferred between stores

A

Mechanically
Electrically
by Heating
by radiation

49
Q

Give examples of where energy is concerved

A

when an object is in an enclosed system

-when a pan, gas, oxygen that heat the pan are in their enclosed surroundings.

50
Q

Give examples of energy being transferred between stores

A

Kettle boiling water- electrical (by heating) to thermal
Rock off Cliff - GPE (mechanically by gravity) to kinetic
Bat and Ball hitting - kinetic (mechanically) to thermal surroundings by heating

51
Q

What happens to wasted energy in energy transfers

A

It is dissipated to surroundings

52
Q

Which ways can energy be wasted by mechanical processes

A

whenever work is done mechanically, frictional forces occur and energy is transferred to thermal stores of whatever is doing the work or surroundings
eg) brakes heating

53
Q

How can we reduce unwanted energy transfers

A

Lubrication- decreases frictional forces

Insulation - decreases energy transfers by heating

54
Q

What does efficiency mean and how can it be increases?

A

Less energy is wasted

-increases with insulation and lubrication by reducing unwanted energy transfers

55
Q

How do you calculate efficiency

A

useful energy / total energy x 100

56
Q

Why does insulating reduce unwanted energy transfers in the home

A

Insulating walls (It has trapped pockets of air) stops conduction

57
Q

What does thermal conductivity mean

A

How well materials transfer heat energy through conduction

58
Q

what effects does thickness of walls and thermal conductivity of a buildiing have on its rate of cooling

A

Thicker the wall the slower the rate of energy transfer. The lower the thermal conductivity of the walls the slower the rate of cooling

59
Q

How do factors effect the gravitational Potential energy stored in an object

A

mass, height, and GFS

60
Q

Name some non renewable energy resources

A

Oil
coal
gas
nuclear

61
Q

Positives an negatives of non renewables

A

+more efficient and reliable

  • finite resource
  • environmental problems : release fossil fuels and oil spills
62
Q

Name some renewable energy resources

A

Biofuels, wind, solar, tidal, hydro-electric

63
Q

Positives an negatives of renewables

A

+never run out
+lower impact on environment
+no emissions
-less reliable can be weather dependent

64
Q

Why can we not use only renewable energy sources

A

because they dont produce as much energy and arent as reliable
eg) solar relies on sun and turbines on wind