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A-Level Physics [Edexcel] > Working as a Physicist > Flashcards

Flashcards in Working as a Physicist Deck (22)
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1
Q

The principle of ‘homogeneity of units’ means:

A

Units in any equation must be the same on both sides

2
Q

State the SI base quantities.

A
Amount of Substance
Current
Distance
Luminocity
Mass
Temperature
Time
3
Q

State the SI base units.

A
Moles (mol)
Amperes (A)
Meters (m)
Candela (cd)
Kilograms (kg)
Kelvin (K)
Seconds (s)
4
Q

The SI derived unit for momentum is:

A

kg m s⁻¹

5
Q

A quantity that has the SI derived unit s⁻¹ is:

A

Frequency

6
Q

A quantity that has the SI derived unit kgm⁻³ is:

A

Density

7
Q

What are the following conversions?

pN→ nN → μN → mN → N → kN → MN → GN → TN

A
p x10⁻¹²
n x10⁻⁹
μ x10⁻⁶
m x10⁻³
-
k x10³
M x10⁶
G x10⁹
T x10¹²
8
Q

The units for strain are:

A

No units

9
Q

A graph with the current on the y-axis and time on the x-axis shows?

A

The current against time

10
Q

What does the gradient of a velocity-time graph represent?

A

Acceleration

∵gradient = Δy / Δx
& velocity (ms⁻¹) / time (s) = acceleration (ms⁻²)

11
Q

What is the dependent variable on a graph?

A

y-axis

12
Q

What is the independent variable on a graph?

A

x-axis

13
Q

What does the area under a force-displacement graph represent?

A

Work Done

∵area = Δy x Δx
& Force x Displacement = Work Done

14
Q

Why do we have base units?

A

These provide a source to derive all other units and ensure that research can be easily compared.

15
Q

What is absolute uncertainty?

A

The uncertainty in a specific measurement

16
Q

What is the unit for absolute uncertainty?

A

It is given in the same units as the original measurement

17
Q

How is the absolute uncertainty stated?

A

It is stated after the measurement as ± [number] [unit].

18
Q

What are three ways to calculate absolute uncertainty?

A
  • half the smallest division on the instrument.
  • half of the last significant figure recorded.
  • half the range of your repeats.
19
Q

What is % uncertainty?

A

It’s how the size of the uncertainty compares to the measurement.

20
Q

How is the % uncertainty stated?

A

It is stated after the measurement as ± [number] %

21
Q

How do you calculate % uncertainty?

A

(the absolute uncertainty / by the average measurement) x 100

22
Q

What happens to the uncertainty when you:

1) add/subtract measurements?
2) multiply/divide measurements?
3) raising measurements to a power?

A

1) add the absolute uncertainties.
2) add the percentage uncertainties.
3) multiply the percentage uncertainty by the power.