1.1 Basic Physics Flashcards
What are SI units?
Fundamental (base) units of physical quantities.
What is the SI unit of mass?
Kg (kilogram)
What physical quantity is measured in mol?
Amount of a substance.
What is the SI unit of current?
Amperes (A)
Is the SI unit for temperature oC or K ?
K (kelvin) as this is the absolute scale.
What is the SI unit of length?
Metres (m)
What quantity is measured in seconds?
Time.
Are Newtons (N) an SI unit?
No, Newtons are not fundamental. The SI units for force are kg m s-2 (Since force = mass x acceleration).
Derive the SI units of energy.
Kinetic energy = 1⁄2 x mass x velocity2 Units = kg x (m/s) x (m/s)
= kg m2 s-2
Derive the SI units of force.
Force = mass x acceleration Units = kg x m s-2
= kg m s-2
Express 60TΩ in standard form.
6 x 1013
(T is tera and the multiplier is 1012)
Write 0.000003m with a suitable prefix.
3μm
What is the actual value of 8MΩ?
8,000,000Ω or 8x106Ω
What is 6000pF in nF?
6nF, as 1 nano unit is 1000 pico units.
What multiplier is associated with the prefix kilo (k)?
x 1000 (103)
What multiplier is associated with the prefix femto (f)?
10^(-15)
Express 7GΩ in standard form
7 x 10(9) Ω
What is 1 eV in J?
1eV = 1.6 x 10-19 J
Express 6 kWh in joules.
6 kW = 6000 J/s
1 hour = 3600s
6kWh = 6000 x 3600
= 21.6 x 106 J
= 21.6 MJ
Convert 6.6 pJ to eV.
6.6 pJ = 6.6 x 10-12 J
7.Divide by 1.6 x 10-19
6.6 pJ = 4.1 x 107 eV (2s.f.)
= 41 MeV
What is meant by a scalar quantity?
A quantity that only has a magnitude.
What is a vector quantity?
A quantity that has magnitude as well as direction.
Is acceleration a vector or scalar quantity?
Vector.
Is mass a scalar or vector quantity?
Scalar.
What equation is used to calculate density?
ρ = m /V
Density = Mass / Volume
Density units: kg m-3
Mass units: kg
Volume units: m3
What is a moment?
A turning force.
Force × perpendicular distance from the point to the line of action of the force
If an object is in equilibrium, the sum of the anticlockwise moments would be…
Equal to the sum of the clockwise moments (principle of moments).
If an object is in equilibrium it means the object is …
Not accelerating. It is either:
● Stationary.
● Moving at a constant velocity.
How can the forces acting on a object be shown to be in equilibrium?
●Adding the horizontal and vertical components of the forces acting on it and showing they equal zero.
●Or if there are 3 forces acting on the object you can draw a scale diagram - if the scale diagram forms a closed triangle, then the object is in equilibrium.
What is meant by a couple?
A pair of equal and opposite coplanar forces that have equal magnitude and opposite direction, applied to a body parallel to each other but not along the same line. For example:
