Prelim Physics Thread (8 Viewers)

[fjitlid]

identify areas of current research and use the available evidence to discuss some of the underlying physical principles used in one application of physics related to waves.
- Gravity waves
- wifi
- adaptive optics
- plasma waves

our textbok has nothing on these. anyone help?

 

[Green Yoda]

identify areas of current research and use the available evidence to discuss some of the underlying physical principles used in one application of physics related to waves.
- Gravity waves
- wifi
- adaptive optics
- plasma waves

our textbok has nothing on these. anyone help?

There is no such dot point?
I recommend doing GPS

 

[eyeseeyou]

Q's

1. When two vectors are being summed together, the reult is known as the resultant vector. Why?
2. Why is the resutant vector determined graphically by head to tail
3. Why is the tail of the second vector placed on the head of the first vector
4. Why is (Q3) continued fro subsequent vectors
5. Why is the resultant vector then the vector joining the tail of the first vector o te head of the final vector?
6. Why does the compass bearing give the angle of the vector relative to the compass points (i.e. N,S,E,W)
7. Why does true bearing give the angle of the vector relayive to the north compass point moving clockwise?
8. Why is the standard units for both (distance and displacement) in metres?
9. Why is the speed a measure of the rate at which an object moves over a distance?

 

[InteGrand]

Q's

1. When two vectors are being summed together, the reult is known as the resultant vector. Why?
2. Why is the resutant vector determined graphically by head to tail
3. Why is the tail of the second vector placed on the head of the first vector
4. Why is (Q3) continued fro subsequent vectors
5. Why is the resultant vector then the vector joining the tail of the first vector o te head of the final vector?
6. Why does the compass bearing give the angle of the vector relative to the compass points (i.e. N,S,E,W)
7. Why does true bearing give the angle of the vector relayive to the north compass point moving clockwise?
8. Why is the standard units for both (distance and displacement) in metres?
9. Why is the speed a measure of the rate at which an object moves over a distance?

1. Because it's the vector that results from the addition.
2. By definition of addition of arrow representation of vectors.
2. By definition of addition of arrow representation of vectors.
4. By definition of addition of arrow representation of vectors.
5. Legitimately by inspection.
6. By definition of compass bearing.
7. By definition of true bearing.
8. By convention (search SI units).
9. By definition of speed.

 

[Nailgun]

Q's

1. When two vectors are being summed together, the reult is known as the resultant vector. Why?
2. Why is the resutant vector determined graphically by head to tail
3. Why is the tail of the second vector placed on the head of the first vector
4. Why is (Q3) continued fro subsequent vectors
5. Why is the resultant vector then the vector joining the tail of the first vector o te head of the final vector?
6. Why does the compass bearing give the angle of the vector relative to the compass points (i.e. N,S,E,W)
7. Why does true bearing give the angle of the vector relayive to the north compass point moving clockwise?
8. Why is the standard units for both (distance and displacement) in metres?
9. Why is the speed a measure of the rate at which an object moves over a distance?

Q1-9. By inspection.

 

[eyeseeyou]

1. Why is velocity the rate of change of displacement as well as its direction?
2. Why is the standard unit for speed&velocity m/s?
3. Why is metres per second represented as (m.s^-1)
4. Why do we often express speed and velocity as averages?
5. Why is speed=dist/time?
6. Why is velociy disp/time?


Are these all "by definition"?

 

[Nailgun]

1. Why is velocity the rate of change of displacement as well as its direction?
2. Why is the standard unit for speed&velocity m/s?
3. Why is metres per second represented as (m.s^-1)
4. Why do we often express speed and velocity as averages?
5. Why is speed=dist/time?
6. Why is velociy disp/time?


Are these all "by definition"?

Yes.

By inspection.

 

[InteGrand]

1. Why is velocity the rate of change of displacement as well as its direction?
2. Why is the standard unit for speed&velocity m/s?
3. Why is metres per second represented as (m.s^-1)
4. Why do we often express speed and velocity as averages?
5. Why is speed=dist/time?
6. Why is velociy disp/time?


Are these all "by definition"?

1. Velocity is just the rate of change of displacement (by definition), which incorporates direction into it.
2. Convention (SI Units for distance is m, for time is s, and velocity is distance/time, so units become m/s).
3. Because m/s is like m s^-1, recalling the definition of x^-1 as 1/x.
4. Because we don't know the instantaneous speeds at all times but can work out average speed by just knowing total distance and total time (plus average speed is often a more useful number to know if we just need a rough estimate or something etc.).
5. Definition.
6. Definition.

 

[eyeseeyou]

1. Velocity is just the rate of change of displacement (by definition), which incorporates direction into it.
2. Convention (SI Units for distance is m, for time is s, and velocity is distance/time, so units become m/s).
3. Because m/s is like m s^-1, recalling the definition of x^-1 as 1/x.
4. Because we don't know the instantaneous speeds at all times but can work out average speed by just knowing total distance and total time (plus average speed is often a more useful number to know if we just need a rough estimate or something etc.).
5. Definition.
6. Definition.

Cheers m8

 

[eyeseeyou]

More Q's:

1. Why does the average speed and the average velocity not provide information about the movement at any particular instant of time?
2. Why does the speed/velocity at any particular time called the instantaneous velocity?
3. We can’t really say anything about the velocity unless we choose a frame of reference?
4. When we measure velocity, we always must have a frame of reference. Why?
5. Why is the ground stationary?
6. Why can we use vector addition to help velocities?
7. Why is the formula: v ½=v1-v2 where v ½ is the velocity od object 1 relative to object 2, v1 is the velocity of object 1 (relative to the ground) and v2=the velocity of object 2 (relative to the ground)
8. When we do relative velocity maths questions, why do we let either the right or left be positive?
9. Why is acceleration a vector quantity?
10. Why is 2 ms/s/s=2m/s^2=2ms^-2?

 

[eyeseeyou]

11. Why is acceleration given mathematically by a=∆v/t where ∆v represents the change in velocity?
12. Why is the change in velocity final velocity-initial velocity
13. Why does positive acceleration represent acceleration (speeding up)?
14. Why does negative acceleration represent deceleration (slowing down)?
15. Why does this (Q 13 and 14) apply if we take the original direction of motion to be positive and if the opposite is chosen, then reverse this?
16. Why is it that for any free falling object on the earth, the object is always subject to a downwards acceleration of approximately 9.8 ms^-2?
17. Why is this acceleration due to gravity (Q16)?
18. Why do we take downwards acceleration as a=9.8ms^-2?
19. Why do we take upwards acceleration as a=-9.8ms^-2?
20. For this question (an object travelling 5ms^-1 to the right is subjected to an acceleration of -2ms^-2 for 2 seconds. What is the final velocity of the object) we let to the right (or left) be positive?

 

[InteGrand]

A lot of these would be by definition or convention.

 

[eyeseeyou]

A lot of these would be by definition or convention.

such as...?

 

[InteGrand]

such as...?

Such as Q.11.

 

[eyeseeyou]

I'll post more here

21. In this question (a vehicle initially travelling with a velocity of 15ms^-1 suddenly accelerates at 5ms^-2 for a period of 10 seconds. Calculate the displacement of the vehicle in this time frame) why do we not let a side be positive or negative?
22. Why do displacement time graphs describe the change in displacement over time?
23. Why does any point along the graph represent the instantaneous object for that given time?
24. Why does rise/run=displacement/time=velocity?
25. Why do velocity time graphs describe the change in velocity over time?
26. Why does any point along the graph represent the instantaneous velocity of the object for that given time?
27. Why is distance a scalar?
28. Why is displacement a vector?
29. Why does acceleration time graphs describe the change in acceleration over time?
30. Why does any point along the graph represent the instantaneous acceleration of the object over the given time?


Also Integrand try to answer all my questions and which ever one's are based on definition, just say "By definition"

 

[eyeseeyou]

31. Why does a force have a vector quantity that has both magnitude and direction?
32. Why is force measured in Newtons?
33. Why can forces be split up into two different main types?
34. Why is direct contact throwing a ball or riding a bike?
35. Why is indirect contact a magnet or earth’s gravity?
36. Why is this a formula? Where is it derived from w=mg?
37. Why on earth is g=9.8ms^-2?
38. Why does the mass of an object never change but the weight may vary depending on location?
39. Why is 9=3.62 on the moon?
40. Why is the result of Newton’s first law inertia?
41. Why do heavier objects have greater inertia?
42. Why do friction forces from the road act on the car to slow it down?
43. Why do air particles exert an external unbalanced force on the plane which slows it down?
44. Why is Newton’s second law of motion f=ma?
45. Why is net force the sum of all acting forces?
46. Why do forces always work in pairs?
47. If you exert a force of 10N to the right on a wall, the wall exerts a force of 10N to the left of you. Why?
48. Why is a normal force always perpendicular to the surface?
49. Why is normal force not a reaction force to weight?

 

[InteGrand]

I'll post more here

21. In this question (a vehicle initially travelling with a velocity of 15ms^-1 suddenly accelerates at 5ms^-2 for a period of 10 seconds. Calculate the displacement of the vehicle in this time frame) why do we not let a side be positive or negative?
22. Why do displacement time graphs describe the change in displacement over time?
23. Why does any point along the graph represent the instantaneous object for that given time?
24. Why does rise/run=displacement/time=velocity?
25. Why do velocity time graphs describe the change in velocity over time?
26. Why does any point along the graph represent the instantaneous velocity of the object for that given time?
27. Why is distance a scalar?
28. Why is displacement a vector?
29. Why does acceleration time graphs describe the change in acceleration over time?
30. Why does any point along the graph represent the instantaneous acceleration of the object over the given time?


Also Integrand try to answer all my questions and which ever one's are based on definition, just say "By definition"

From a quick glance, Q.22 to Q.30 are by definition.

 

[eyeseeyou]

R U an expert in chemistry Integrand?

 

[turntaker]

R U an expert in chemistry Integrand?

I am

 

[calamebe]

My teacher gave me a sheet today for which we have to graph displacement-position graphs of waves. I'm kinda confused, as displacement and position are the same thing, at least going off the motion topic. So is there any kind of difference in the definition of these terms for waves, or is it most likely a typo (I find that a bit unlikely though as it has it many times)