Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physics > Mechanics and Special Relativity > Flashcards

Mechanics and Special Relativity Flashcards

1
Q

What is A•B physically?

A

The magnitude of A multiplied by the component of B in the direction of A.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What A•B mathematically?

A

|A||B|cosx

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Is A•B = B•A?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

A•B in terms of components?

A

AxBx + AyBy + AzBz

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

A•A=?

A

(|a|)^2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is Einstein’s first postulate?

A

The laws of physics are the same in every inertial frame of reference.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is Einsteins second postulate?

A

The speed of light in vacuum is the same in all inertial frames of reference and is independent of the source.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the speed of light?

A

2.998x10^8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What 3 conclusions are drawn from Einsteins postulates?

A
  • No absolute ruler length
  • No absolute clock
  • Simultaneity depends on the observers.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the Lorentz factor (equation)?

A

Y=(1-(u/c)^2)^-1/2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Do moving clocks tick fast or slow?

A

Slow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Time dilation equation

A

t=y•t0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why can massive objects not move at the speed of light?

A

Because it would require infinite energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is proper time?

A

Time as measured by an observer with a stationary clock (at the same location as the observer).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is proper length?

A

The length of a body in a reference frame at which the body is at rest.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Do moving bodies contract or lengthen according to a stationary observer?

A

Contracts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Equation of length contraction?

A

L = L0/Y

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How are lengths parallel and perpendicular to the direction of motion affected?

A

Parallel - contracted by factor of 1/y

Perpendicular - unaffected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a unit vector?

A

A vector that has magnitude 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What’s Newton’s first law?

A

In the absence of a net force a body at rest will remain at rest, bodies in uniform motion will remain in uniform motion at constant velocity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What’s Newton’s second law?

A

F=ma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What’s Newton’s third law?

A

For every action, there is an equal and opposite reaction.

23
Q

Evaluate the frictional force on a body.

A

F = uN in opposite direction to direction of motion.

24
Q

Which is bigger? Coefficient of friction when static or in motion?

A

Static

25
Q

Fluid resistance at low velocity?

A

F = kV where k is viscosity

26
Q

Fluid resistance at high velocity?

A

F = DV^2 where D is drag.

27
Q

Work done =?

A

Wd = S F•ds

Path

28
Q

How is the work done on an object and its kinetic energy related.

A

Wd = 🔼KE

29
Q

What’s Hooke’s law?

A

Force on a mass due to a spring = -kx

30
Q

What is the potential energy of a spring compressed or stretched by x from equilibrium?

A

U = (kx^2)/2

31
Q

What is the speed of a mass compressed or stretched by X from equilibrium when it passes through equilibrium after release?

A

V=X•sqrt(k/m)

32
Q

Equation of momentum?

A

P=mv

33
Q

How does force affect momentum?

A

F = dP/dt

34
Q

What is impulse?

A

🔼P = F x 🔼t for small 🔼t

35
Q

What is a perfectly elastic collision?

A

Bounce off, KE is conserved

36
Q

What is a perfectly inelastic collision?

A

Stick together, energy dissipated into deformation.

37
Q

Velocity of the centre of mass =?

A

V = Ptotal/M

38
Q

What is the change in velocity of rocket of mass M ejecting gas of mass m at speed v?

A

🔼V = mv/M-m

39
Q

What is the acceleration of a rocket that is constantly ejecting gas at rate of dM/dt = c?

A

a= - vgas/M * c

40
Q

Calculate angular frequency from linear speed and radius

A

w = V/r

41
Q

Calculate the frequency of rotation from the angular frequency.

A

f=w/2pi

42
Q

What is the centripetal acceleration of an object (equation)?

A

a = w^2*r towards centre of circle

43
Q

What is the acceleration of a mass oscillating on a spring?

A

a = -kx/m

44
Q

For a small x what’s the approximation for cosx?

A

1 - x^2/2

45
Q

For small X what’s the approximation of sinx?

A

X

46
Q

What’s the angular frequency of a pendulum of length L?

A

w = sqrt(g/L)

47
Q

What’s the frequency of a pendulum of length L?

A

T = 2pi*sqrt(L/g)

48
Q

What is a physical pendulum?

A

Any real pendulum that uses an extended body.

49
Q

What is the angular frequency of a physical pendulum?

A

w = sqrt(I/mgd) where I is moment of inertia and d is distance from rotational axis to centre of gravity.

50
Q

What is the force on a mass undergoing damped SHM?

A

F = -kx -bV

51
Q

What is the decay timescale in damped SHM?

A

The time for the amplitude to be reduced by a factor of e.

52
Q

What is the angular frequency of a slightly damped oscillator?

A

w’ = sqrt(k/m - b^2/4m^2)

53
Q

What is the amplitude of a forced oscillator?

A

A = ______F_max_______________
Sqrt((k-mw^2)^2 + (bw)^2

Where w is driving angular frequency and b is the damping constant.

54
Q

What is the classical mechanics limit?

A

V

Physics (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions