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Flashcards in Physics - Final Deck (78)
0

What is terminal velocity? (3)

Is work being done?

When the upward forces of air resistance balances the downward force of gravity

Net force = 0

Yes, work is being done, because the object's gravity moves the object downward with a constant maximum speed, and the forces are getting balanced out by air resistance

1

What is the distance formula?

Df = di + vt + 1/2at²

2

Scalar vs vector

Scalar - only has magnitude

Vector - magnitude and direction

3

The quadratic equation is used with values in which direction?

The y-direction

4

What is the path of a projectile called?

What shape does it form? (2)

A trajectory

Parabola

5

What is Newton's second law? (2)

F = ma

Measured in Newtons --> kg•m/s²

6

What is the fundamental unit of force? (2)

F = ma
F= kg•m/s² or N

7

When an object is moving at constant velocity, how do you determine net force? (2)

Net force = 0
A = 0

8

Define inertia

Describes how much it will resist change to the motion of the object

9

What is the formula for the weight of an object directed down an inclined plane

Weight = mass • gravity

10

Units of the coefficient of friction?

There are no units

11

How to find the angle of slippage if given the coefficient of static friction

Ff = μsFn --> μsmgcosθ --> Ff/μsmg = cos θ⁻1

12

List the 3 types of friction in order of weakest to strongest (3)

1. Rolling
2. Kinetic
3. Static

13

When an object begins to slide down a ramp, which two forces are equal?

The x and y components

14

What is the equation for the force of kinetic friction on a flat surface?

μkmg

15

Unit for energy?

Joule

16

What is the conservation of energy equation for the velocity of an object at the bottom of the ramp (with friction)? (2)

PE - Ff = KE

V= √2g(h-μkcosθd)

17

What is the formula for work done by friction down an inclined plane?

Wf = μkmgcosθd

18

What are the fundamental units of power? (2)

P = w/t --> kg•m²/s³

W= fd --> kg•m²/s²

19

If the sun were to suddenly disappear, what would happen to the path of the earth?

It would go in a straight line

20

Under what circumstances will the quadratic formula provide two real roots?

When an object passes a certain point twice

21

The metric system

Based on powers of 10

22

10mm = cm

10mm = 1cm

23

10cm = dm

10cm = 1 dm

24

10dm =

10dm = 1m

25

Basic trig functions (4)

Tan θ = Δy / Δx

D = √Δx²+Δy²

Sin θ = Vy/V or Δy/d

Cos θ = Vx/V or Δx/d

26

Matric prefixes (9)

Nano- 10⁻⁹
Micro- 10⁻⁶
Milli- 10⁻³
Centi- 10⁻²
Deci- 10⁻¹
Deka- 10
Kilo- 10³
Mega- 10⁶
Giga- 10⁹

27

Calculating line of best-fit (2)

Calculate by using y=mx+b

y-y₁=m(x-x₁)

28

Distance vs displacement (2)

Distance - total distance traveled

Displacement - change in position of an object

29

Speed vs velocity (2)

Speed - scalar quantity

Velocity - vector quantity

30

Velocity vs acceleration (2)

Velocity - rate of change in distance

Acceleration - rate of change in velocity

31

How to find X and Y components (4)

Vx = dx/t
Vy = dy/t

Vx = Vcosθ
Vy = Vsinθ

32

How to solve advanced projectile motion problems? (3)

1. find x component using dx=Vx•t
2. Find velocities for x and y component using Vx=V(cosθ) and Vy=V(sinθ)
3. Find t using distance formula going in the y-direction --> dfy=diy+vt+1/2at²

33

Projectile motion

Refers to the motion of an object that is thrown, or projected into the air at an angle

34

Free-fall acceleration

The vertical motion of a projectile with a constant downward acceleration due to gravity

35

Direction of gravity? (2)

Downwards; not horizontally at all

36

There are two objects: one is thrown and one is dropped. Which one will land with the shortest time?

They will finish landing with the same time

37

What are the circumstances for negative velocities?

Velocities are negative as an object goes back down

38

How the distance formula can be reduced to simpler forms? (2)

D = 1/2at²

T = √2d/g

39

Resultant

The hypotenuse of a Pythagorean theorem triangle

40

What is Newton's first law?

Law of inertia - an object at rest tends to stays at rest and an object in motion tends to stay in motion unless acted upon by an unbalanced force

41

Define weight

A measure of the force of gravity on the mass of an object

42

What is Newton's third law?

For every action there is an equal and opposite reaction

43

Net force (4)

Causes acceleration

No acceleration = no net force

Net force = acceleration/mass

Net force = mgcosθ + mgsinθ

44

What force is ignored in projectile problems?

Air-resistance

45

Action-reaction pair "force pairs"

A pair of simultaneous equal but opposite forces resulting from the interaction of two objects

46

Static friction (5)

The resistive force that opposes the relative motion of two contacting surfaces that are at rest with respect to one another

A = 0
Net force = 0

The friction caused by the microwelds is the opposing force that cancels out the force applied

Ex. A boy pushing a box but it is not moving

47

Kinetic friction

How is kinetic friction caused? (2)

The resistive force that opposes the relative motion of two contacting surfaces that are moving past one another

Caused by microwelds breaking and then forming again as two surfaces rub against each other

48

The normal force (Fn) (2)

The supporting force that acts on the object perpendicular to the surface plane

Fn = mg

49

Friction

A resistive force that acts in a direction opposite to the direction of the relative motion of two contacting surfaces

50

What causes friction?

Microwelds; two bumpy surfaces that rub up against each other and stick together to produce microwelds

51

How to calculate the force of friction? (Ff)

Ff = μFn --> μmgcosθ

52

How to find the coefficient of kinetic friction? (3)

μk = Fk/Fn

Fk = μkmg

Fn = mg

53

How to solve tension problems (5)

1. Set forces in x and y equal
Ty₁ + Ty₂ = mg
Tx₁ = Tx₂

2. Put Ty₁, Ty₂, Tx₁, and Tx₂ in terms of T₁ and T₂
T₁sinθ + T₂cosθ = mg

3. Set T₁ in terms of T₂ and Substitute
Because T₁ = T₂, this is possible.
Do T₁sinθ₁ + T₂sinθ₂ = mg
4. Solve for T₁
5. Go back and solve for T₂
T₁ = (T₂cosθ)/ cosθ

54

Define force

The cause of an acceleration or the change in an objects velocity

55

Define energy

The ability to change or cause change

56

No energy =

No energy = no change

57

Potential (4) vs kinetic energy (3)

Potential:
- energy of what might happen
- potential to change
- unit = Joule (kg•m²/s²)
- Ep = mgh

Kinetic:
- energy of motion
- unit = Joule
- Ek = 1/2mv²

58

Define work (3)

A transfer of energy

W = force x distance

Unit = Joule = 1 N • m

Only done when components of a force are parallel to a displacement

59

What results from no work being done?

No change in kinetic energy and potential energy = no work done

60

How to find work done by a constant force?

W = Fd(cosθ)

61

How to find the net work done by a constant net force?

Wnet = Fnet•d•(cosθ) --> μkmgcosθd

62

Other ways to find net work? (2)

Wnet = m[(Vf²-Vi²)/2]

Wnet = ΔKE (change in kinetic energy)

63

Gravitational potential energy (3)

The potential energy associated with an object due to the position of the object

PEg = mgh

H = 0

64

Power (5)

Rate at which energy is transferred

P= work/time

P= kg•m²/s³ (Watts)

P = F(d/t) <---- W=Fd

P = Force•velocity

65

Conservation of energy

Energy can change form; it can't be destroyed nor created

66

Where does missing energy go? Possible sources of "lost energy"? (3)

Friction

Gravity / free-fall acceleration

Air resistance***

67

Similarities and differences between work and force? (2)

Similarities- both involve forces that cause accelerations

Differences - can have a force w/ no motion, but you can't have WORK w/o motion

68

How is power related to work and forces?

Power is the rate at which work is being done and work involved forces

69

When the net work of an object = 0... Is the object moving?

Needs more info. It can be moving at a constant velocity or it could be standing still

70

When would you set forces equal to each other? (3)

When velocity is constant

When acceleration = 0

When Fnet = 0

71

Dimensional analysis of PE, KE, work, and power? (4)

PE = mgh --> kg•m²/s²

KE = 1/2mv² --> kg•m/s²

Work = Fd --> kg•m²/s²

Power = w/t --> kg•m²/s³

72

How to find force at an angle?

F = mgsinθ

73

How to find a using force at an angle?

A = gsinθ

74

How to find work done by someone

W = Fd

75

How to find work done by gravity

W = mgh

76

How to find x and y components of work? (2)

Wx = mgcosθd

Wy = mgsinθd

77

Weight down an inclined plane

Mgsin = weight down an inclined plane