Topic 111

Question 1

Describe:

Relationship between launch angles that result in the same range.

Answer 1

Is an angle of theta, and theta-90

Equal distance from 45 degrees

Question 2

Explain:

Factors that affect drag and what results of drag and how can it be applied

Answer 2

Speed, cross sectional area, shape and density of medium changed drag force and results in terminal velocity when the magnitude of drag force results in 0 net force on moving body such as skydiving.

Question 3

Describe:

Newton’s laws of motion

Answer 3

1st, law of inertia
2nd, F=ma
3rd, F1=-F2

Question 4

Describe:

Momentum in relation to newton’s laws

Answer 4

Is the product of an object’s mass and velocity in Sec newtons.
sN
With newton’s second law: F=(delta p) / (delta t)

Question 5

Describe:

What newton’s third and second law implies.

Answer 5

The law of conservation of momentum is implied by F1=-F2 and F=ma, as momentum is conserved in an isolated environment.
(delta p1) / (delta Dt1) =- [ (delta p2) / (delta t2) ]
(mv)1f - (mv)1i = -[ (mv)2f - (mv)2i ]
(mv)1f + (mv)2f = (mv)1i + (mv)2i
Initial momentum = final momentum

Question 6

Define:

Centripetal acceleration

Answer 6

The acceleration experienced by an object undergoing circular motion acting at right angles to the velocity, towards the center of the turn. Its magnitude is given by:
a=v^2/r

Question 7

Explain:

What a banked turn can do to a driving car

Answer 7

Reduces reliance on friction applying centripetal acceleration. The road provides a normal force which is resolved into 2 vectors, one that provides centripetal acceleration.

Question 8

Explain:

How to find optimum banked angle ness

Answer 8

Using the equation:

Tan() = v^2 / rg

Question 9

Describe;

Law of conservation of momentum

Answer 9

Newton’s third and second laws imply that total momentum of an isolated system is constant assuming forces are only acted on one another.

Question 10

Describe:

Ion thrusters

Answer 10

Through law of conservation of momentum, from newton’s 3rd law, the expulsion of accelerated ions with momentum away from the craft will result in the craft gaining momentum in the opposite direction.

Question 11

Describe:

Solar sails

Answer 11

Through law of conservation of momentum, from newton’s 3rd law, the reflection of light photons upon a sail will result in a force acted on the sail by the change in photons momentum:
F(sail) = (delta p)sail / (delta t), and thus acceleration by:
A = f/m

Question 12

Describe:

How an object may travel in a circular path

Answer 12

Going through uniform circular motion, the object undergoes centripetal acceleration, which is directed towards the centre of the circle.
With radius a=v^2/r

Question 13

Describe:

Gravitational force and gravitational field strength

Answer 13

Objects with mass produce a gravitational field, other objects with mass experience a gravitational force when in the gravitational field of another mass towards said mass.

Field strength, g, is the net force per unit mass at a point in the field.

Question 14

Define:

Newton’s law of universal gravitation

Answer 14

Every body in the universe attracts every other body with a force that is directly proportional to the product of the two masses and inversely proportional to the square of the distance between them.

Question 15

Explain:

gravitational forces are consistent with newton’s third law

Answer 15

As every force has an equal and opposite force, the gravitational forced induced onto object 1 by object two is equal to the gravitational force induced onto object 2 by object 1

Question 16

Explain:

Why centers of circular orbits must coincide with earth’s center of mass.

Answer 16

As the gravitational force which provides centripetal acceleration is directed to the earth’s centre of mass, if a satellite was not orbiting around the centre, the gravitational force would not be at right angles to the satellites motion, thus pulling the satellite into earth

Question 17

Derive:

V= Root(GM/r)

Answer 17

As F=(Gmm)/r^2 and F=ma, a=(V^2)/r

F=(Gmm)/r^2=(MV^2)/r
Root(GM)/r = V

Question 18

Describe:

Kepler’s first 2 laws of planetary motion

Answer 18

All planets move in elliptical orbits with the sun at one focus
A radius vector drawn from the sun to a planet sweeps equal areas in equal time intervals.

Question 19

Derive:

Keplars third law of motion

Answer 19

T^2 = 4pi^2 / GM x r^3

As V=root(GM)/r and V = (2Pir)/T

(GM)/r = (4pi^2r^2)/T^2 
T^2 = 4pi^2 / GM x r^3

Question 20

Explain:

Geostationary orbit factors

Answer 20

To be geostationary it needs to have a period of 24 hours and thus it needs to have a large radius.
Must travel in the same direction as earth’s rotation.

Question 21

Identify:

Applications of all the orbits.

Answer 21

Geostationary: large land coverage, communication between ground stations.
Large distance results in low quality images

Polar: High quality images, with other polar sats to produce large weather maps
Only observes parts of the earth each day

Question 22

State:

Newton’s postulates of relativity

Answer 22

The speed of light in a vacuum is an absolute constant

The laws of physics are the same in all inertial reference frames

Question 23

Define:

t(zero) from t=yt(zero)

Answer 23

T zero, is the time interval in the moving frame of reference and t is the time in the stationary observer’s frame of reference.

Question 24

Explain:

What occurs for a super fast object in an observer’s reference frame.

Answer 24

Time is slowed, mass increases, length contracts in direction of motion

Question 25

Define:

Proper length

Answer 25

l(zero) is the length of an object measured in a stationary frame.