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Zhang's > Mod 5 > Flashcards

Mod 5 Flashcards

1
Q

Define Uniform Circular Motion (UCM)

A

Uniform Circular Motion is when an object travels in a circle at a constant rate

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2
Q

Identify features of Uniform Circular Motion (UCM)

A

Features of Uniform Circular Motion:
- Constant speed
- Constant acceleration - magnitude
- Constant force
- Changing direction of velocity
- Zero displacement
- Fixed centre and radius
- Zero net force

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3
Q

Identify the driving force for Uniform Circular Motion (UCM)

A

Centripetal force drives uniform circular motion

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4
Q

Centripetal Acceleration

A

a = (v^2)/r

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5
Q

Centripetal Force

A

F = (mv^2)/r

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6
Q

Explain why centripetal force is not drawn in force diagrams

A

In uniform circular motion, centripetal force is the net force and hence, is not drawn in force diagrams

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7
Q

True or False. Calculations of Uniform Circular Motion (UCM) has to be performed in radians

A

True. Using degrees will result in incorrect solutions

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8
Q

Linear velocity - UCM

A

v = r * ω

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9
Q

Angular velocity - UCM

A

ω = (2π)/T

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10
Q

True or False. Conical Pendulum is an example of Uniform Circular Motion (UCM)

A

True. Note: It is only uniform circular motion if the motion of the weight forms a circle - hence, or ‘conical’

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11
Q

Define banked track

A

A track with a tilt towards the centre to assist in turning

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12
Q

Compare and contrast banked tracks with a slope

A

Although both are inclined, a bank track = N > mg and a slope = N < mg

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13
Q

Define torque

A

Torque is the rotational effect that a force has on an object

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14
Q

Identify whether torque is a vector or scalar quantity

A

Torque is a vector quantity. Torque is the cross-product of 2 vector quantities

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15
Q

Torque

A

Τ = rFsin(θ)

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16
Q

True or False. An object with no net force has no net torque

A

False. Force is linear and torque is rotational - hence 2 separate components

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17
Q

Define rotational equilibrium

A

Rotational Equilibrium is when the net torque = 0; there is no overall rotational effect within the system

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18
Q

Define inertia

A

Inertia refers an object’s tendency to resist motion

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19
Q

Inertia

A

I = mr^2

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20
Q

Define orthogonal

A

Orthogonal is when vectors are perpendicular in 3D space

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21
Q

Define critical speed

A

Critical speed is when under zero friction the minimum speed necessary to remain in uniform circular motion

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22
Q

Gravitational Force

A

F = (Gm1m2)/(r^2)

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23
Q

Explain why the force between masses is the same regardless of individual masses

A

The force is equal due to Newton’s Third Law of Motion - equal and opposite forces

24
Q

Gravitational Field Strength

A

g = (GM)/(r^2)

25
Q

Define mass

A

Mass is the amount of particles in an object

26
Q

Define weight

A

Weight is the gravitational attraction force acting upon a body’s mass

27
Q

True or False. Gravitational field lines only facilitate attraction force.

A

True.

28
Q

Identify the factors that impact gravitational strength

A

Factors that impact gravitational strength:
1. Earth is not an oblate spheroid
2. The surface is not uniform
3. The density of the Earth is not uniform
4. Psuedo Effect

29
Q

Outline the Psuedo Effect

A

The Psuedo Effect occurs due to the rotation of the Earth which counteracts the normal force, creating the perception of weaker gravitational strength.

30
Q

Identify where the Psuedo Effect is most evident. Elaborate

A

The Psuedo Effect is most evident at the equator as the radius of the Earth is most significant

31
Q

Outline the derivation of critical speed

A

Net force = 0
Both the vertical and horizontal components = 0, hence:

equate - v^2 = rg tan(θ)

32
Q

Outline the derivation of orbital velocity

A

As the gravitational force supplies the centripetal force, equate:

v^2 = (GM)/r

33
Q

Identify what you notice about the orbital velocity. Elaborate.

A

The mass of the orbiting object is not a factor in velocity. This can be explained through the conservation of energy as the kinetic energy is transferred into gravitational potential energy and the ‘m’ is cancelled out.

34
Q

State Kepler’s 1st Empirical Law

A

Orbits about the sun are elliptical where the sun is located at one of the two foci

35
Q

State Kepler’s 2nd Empirical Law

A

The line between the orbiting object and the object being orbited sweeps out equal area for a given time interval.

36
Q

Kepler’s 3rd Empirical Law

A

(r^3)/(T^2) = (GM)/(4π^2)

37
Q

Identify the types of Earth orbits

A

Types of Earth Orbits:
- Lower Earth Orbit (LEO)
- Geostationary Orbit
- Geosynchronous Orbit

38
Q

Discuss the advantages and disadvantages of Lower Earth Orbit

A

Advantages:
- Not significant energy necessary
- Can clearly monitor Earth’s surface
- Insignificant signal delay

Disadvantages:
- Orbital decay
- Satellite dishes have to rotate and coordinate with the satellites

39
Q

Define orbital decay

A

Orbital Decay is the collisions between the molecules in the upper reaches of the atmosphere and the satellite, creating significant drag force

40
Q

Define geostationary orbit

A

Geostationary orbit is at an altitude of 35, 780 km, precisely matching the period of the orbits with the Earth - appearing above the same point on Earth at all times

41
Q

Compare and contrast geostationary orbit and geosynchronous orbit

A

Although both are at the same altitude - 35, 780km - a geostationary orbit is in the equatorial plane and a geosynchronous orbit is not and it forms a figure-8 shape instead

42
Q

Explain why the gravitational potential energy is always negative

A

Gravitational potential energy is always negative as an infinite distance away is considered the Zero Reference Point

43
Q

Gravitational Potential Energy

A

U = -(GMm)/r

44
Q

True or False. Gravitational potential energy is of a significant value close to planetary masses. Link visually

A

False. Gravitational potential energy is of an insignificant value close to planetary masses. This is depicted through ‘potential wells’ graphically

45
Q

Derivation of Total Mechanical Energy

A

TME = KE + GPE

Use orbital velocity - hence limited to orbital motion

TME = -(GMm)/(2r)

46
Q

Define escape velocity

A

Escape velocity is the minimum speed at which an object needs to be launched from the surface in any direction such that it will completely exit the gravitational field

47
Q

Derivation of escape velocity

A

Equate the change in kinetic energy and gravitational potential energy, where initial kinetic energy = 0 and final gravitational potential energy = 0

v^2 = (2GM)/r

48
Q

True or False. The escape velocity of an object is independent of its mass

A

True

49
Q

Identify the shape of the flight of an object below escape velocity

A

Shape of Flight:
- Ellipse
- Circle

50
Q

Identify the shape of the flight of an object exceeding escape velocity

A

Shape of Flight:
- Parabola
- Hyperbola

51
Q

Identify the types of orbital transfer manoeuvre

A

Movement between orbits:
- Low to High
- High to Low

52
Q

Define perigee

A

The point in the orbit nearest to the planetary mass based on geometric centre

53
Q

Define periapsis

A

The point in the orbit nearest to the planetary mass based on density core

54
Q

Define apogee

A

The point in the orbit furtherest to the planetary mass based on geometric centre

55
Q

Define apoapsis

A

The point in the orbit furtherest to the planetary mass based on density core

56
Q

Compare and contrast weightlessness and apparent weightless

A

Weightlessness is when gravity does not act on an object; g = 0. Apparent weightlessness is when the object cannot feel the sensation of weight; the normal force = 0.

57
Q

Define artificial gravity

A

In the absence of gravity, the sensation of gravity can be evoked (N = g)

Zhang's (4 decks)

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