1.1 Basic Physics Flashcards Preview

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Flashcards in 1.1 Basic Physics Deck (40)
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1
Q

7 SI quantities

A

Mass, length, time, current, temperature, amount of substance, luminous intensity

2
Q

7 SI base uits

A

kg, m, s A, K, mol, cd

3
Q

How to find base units

A
  1. Find equation
  2. Find known units in equation
  3. Solve equation
4
Q

An equation must be

A

homogeneous to be correct

5
Q

Homogeneous

A

Means the units are equal on both sides

6
Q

If 2 vectors are at 90 degrees you can add them using

A

sin(theta) = opposite/ hypotenuse

7
Q

A vector quanitity

A

has magnitude and direction

8
Q

A scalar quantity

A

has just magnitude

9
Q

Velocity=

A

displacement/ time

10
Q

Acceleration=

A

change in velocity/ time

11
Q

List of scalars

A
Density
Mass
Volume
Area
Distance
Length
Speed
Work
Energy
Power
Time
Resistance
Temperature
Voltage/ PD
Charge
Pressure
12
Q

List of vectors

A
Displacement
Velocity
Acceleration
Force
Momentum
Gravitational Field Strength
13
Q

To add more than one vector

A

Add them nose to tail

14
Q

To subtract vectors e.g. v2-v1

A

-v1 + v2

15
Q

Finding the component of a force is called

A

resolving; we resolve a force into its horizontal and vertical components

16
Q

Components of vectors using trig

A
Fh = Fcos(theta)
Fv = Fsin(theta)
F = Root{Fh^2 + Fv^2}
17
Q

Density (p)=

A

mass/ volume

18
Q

Density of air at 0 degrees

A

1.29 kgm^-3 or 0.00129 gcm^-3

19
Q

Density of water

A

1000 kgm^-3 or 1 gcm^-3

20
Q

Density of brick

A

2300 kgm^-3 or 2.3 gcm^-3

21
Q

Density of petrol

A

880 kgm^-3 or 0.88 gcm^-3

22
Q

Density of steel

A

7900 kgm^-3 or 7.9 gcm^-3

23
Q

Density of aluminium

A

2800 kgm^-3 or 2.8 gcm^-3

24
Q

Density of mercury

A

13600 kgm^-3 or 13.6 gcm^-3

25
Q

Density of gold

A

19300 kgm^-3 or 19.3 gcm^-3

26
Q

1 cm^3=

A

1 x 10^6 m^-3

27
Q

1000 kgm^3=

A

1gcm^-3

28
Q

Moment=

A

force x perpendicular distance

29
Q

The moment of a force is also called

A

its torque; the symbol t is also sometimes used

30
Q

The moment of a force is

A

the product if the force and the /perpendicular/ distance from the point to the line of action of the force

31
Q

Moments can be

A

clockwise or anticlockwise

32
Q

The principle of moments:

A

for a body to be in equilibrium under the action of a number of forces, the resultant moment about any point is zero- the sum of the clockwise moments is equal to the sum of the anticlockwise moments about the same point

33
Q

The centre of gravity is the point at which

A

we can consider all the object’s weight to act

34
Q

(In a uniform gravitational field) the C of G of a symmetric body of uniform density

A

will lie on any plane of symmetry

35
Q

For a standing object, to be more stable

A

it should have a lower C of G and a wider base

36
Q

A body is said to be in equilibrium if

A

it is moving and rotating at a constant rate

37
Q

In order to be in equilibrium

A

the resultant force on the object must be zero and the resultant moment about any point must be zero

38
Q

PRACTICAL: Measuring mass using the principle of moments

A
  • Use known distances and one known mass
  • Move the unknown mass until the ACM and CM are equal
  • Calculate
39
Q

PRACTICAL: Absolute uncertainities

A

Often taken as +- 1 of the last digit of reading

40
Q

PRACTICAL: Measuring the density of solids

A
  • Measure mass
  • Measure volume
  • Divide mass by volume
    Regular solids/ irregular solids (measure/ liquid displacement)