Forces and Motion Flashcards

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1
Q

What is the equation for speed?

A

speed = distance/time

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2
Q

What is the equation for weight?

A

weight = mass x gravity

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3
Q

What is the equation for acceleration?

A

acceleration = change in velocity/time

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4
Q

What is the relationship between force, mass, and acceleration?

A

force = mass x acceleration

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5
Q

What does the gradient in a distance time graph represent?

A

speed

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6
Q

What does the gradient in a velocity time graph represent?

A

acceleration

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7
Q

What does a curving line represent on a distance time graph?

A

acceleration/ deceleration

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8
Q

What does a curving line represent on a velocity time graph?

A

increasing acceleration / deceleration

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9
Q

What does a horizontal line represent on a distance time graph?

A

stopped

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10
Q

What does a horizontal line represent on a velocity time graph?

A

steady speed

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11
Q

What IS acceleration?

A

the rate of increase of velocity with time

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12
Q

Why do objects reach terminal velocity?

A

when an object has the balanced forces of air resistance and weight on it. It falls at a constant speed. The two examples are a sky diver and sycamore seeds.

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13
Q

How do you find distance from a velocity time graph?

A

area under graph

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14
Q

What is the unit for velocity?

A

m/s

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15
Q

What is the unit for acceleration?

A

m/s2

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16
Q

What is the unit for force?

A

Newtons

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17
Q

What is the unit for momentum?

A

kg m/s

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18
Q

What is the unit for volume?

A

m3

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19
Q

What is the fancy unit for temperature?

A

Kelvin (-273°C)

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20
Q

What is the difference between a vector and a scalar quantity?

A

a vector quantity has both direction and magnitude, where as a scalar quantity just has magnitude.

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21
Q

What IS friction?

A

the force which opposes motion

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22
Q

Use ideas about molecules to explain how pressure is caused inside an object.

A
Any three of
MP1. idea of (continuous) random
movement;
MP2. collisions / impact/eq;
MP3. with (inside) walls;
MP4. idea that force is produced (by
bombarding molecules);
MP5. idea of pressure as force on an
area;
23
Q

What is the equation for gravitational potential energy?

A

gravitational potential energy = mass x gravity x height

24
Q

What is the equation for refractive index?

A

n = sin i/ sin r

25
Q

What is Newton’s third law of motion?

A

for every action, there is an equal and opposite reaction

26
Q

What does stopping distance consist of?

A

thinking distance = braking distance

27
Q

What 2 things affect thinking distance?

A
  • speed

- state of driver (eg. old age, tiredness, dugs, alcohol, inexperience?

28
Q

What 4 things affect breaking distance?

A
  • speed
  • mass of vehicle
  • quality of brakes
  • grip (road surface, weather, tyres)
29
Q

What is the equation for momentum?

A

momentum = mass x velocity

30
Q

What is the unit for momentum?

A

kg m/s

31
Q

Momentum before and momentum after are…

A

equal

32
Q

What is the relationship between force, momentum and time?

A

force = change in momentum/time

33
Q

How does a crumple zone help?

A

increases the time for the change in momentum to happen, therefore reducing the force on the car.

34
Q

What is the equation for moments?

A

moment = force x distance

35
Q

What is the unit for moments?

A

Newton meters (Nm)

36
Q

Where does the weight of a body act on an object?

A

centre of gravity

37
Q

What is the principle of moments for a balanced object?

A

total anticlockwise moments = total clockwise moments

- if this is not true, there will be a resultant movement and the object will turn

38
Q

What is Hooke’s law?

A

extension is directly proportional to force

39
Q

What is elastic limit? What happens past it?

A

when a material stops obeying hooke’s law. If the force is increased past the elastic limit, the material will be permanently stretched, and will not return to its original shape.

40
Q

Elastic behaviour is shown when…

A

a material returns to its original shape after elastic deformation.

41
Q

Is force a scalar or vector quantity?

A

vector

42
Q

Our solar system is part of our…

A

galaxy

43
Q

What is a galaxy?

A

a huge collection of stars

44
Q

What is the universe?

A

a large collection of billions of galaxies`

45
Q

What causes orbits?

A

gravity pulls the objects inwards towards the planet/star, as it is trying to constantly change direction.

46
Q

How do planets obit?

A

slightly elliptically

47
Q

Two things in orbit of the earth

A

the moon, artificial satellites

48
Q

In orbits, the further away an object is from the thing it’s orbiting

A

the weaker the gravity and the force of attraction

49
Q

How do comets obit?

A

very elliptically

50
Q

What is a geostationary satellite and what is it useful for?

A

has an orbital period of exactly one day, useful for communications.

51
Q

Describe an experiment to investigate motion

A
  • toy car on a ramp using light gates to find the car’s average speed
  • connect light gates to computer and repeat to make it more reliable
  • to calculate average speed of car divide distance between light gates by time taken
  • you could change mass of car, different materials for friction, change ramp to see acceleration due to gravity, angle of ramp, different cars
52
Q

Describe an experiment to investigate terminal velocity

A
  • sycamore seeds
  • measure mass and wing length of different seeds
  • use seeds with either same wing length or same mass to keep variables constant
  • drop from same height and record time (higher = better cos improves accuracy)
  • repeat and find average
  • draw graph of wing length against time to show relationship between seed size and terminal velocity
53
Q

Why are sycamore seeds used when investigating terminal velocity?

A

they have a small weight and large surface area so reach terminal velocity quickly