Unit 1.1 Basic Physics Flashcards
What are SI units?
Fundamental (base) units of physical quantities.
What is the SI unit of mass?
Kilogram (Kg)
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 C° or K?
K (kelvin) as this is the absolute scale.
What is the SI unit of length?
Metres (m)
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 = ½ × mass × 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 (3 micro meters) (The factor of micro is 10⁻⁶ so move the decimal place 6 times to the right).
What is the actual value of 8MΩ?
8,000,000Ω or 8x10⁶Ω
What is Ω?
Resistance (gwrthiant)
What is 6000pF in nF? (p=10⁻¹² and n=10⁻⁹)
6nF as 1 nano unit is 1000 pico units.
What multiplier is associated with the prefix kilo (k)?
x1000 (10³)
What multiplier is associated with the prefix femto (f)?
10⁻¹⁵
Express 7GΩ in standard form.
7 x 10⁹ Ω
What is 1 eV in J?
1eV = 1.6 x 10⁻¹⁹ J
Equilibrium
A body is in equilibrium if it’s moving and rotating at a constant rate. (Can be still).
- The resultant force on the object must be zero
2.The resultant moment (about any point) must be zero (the principle of moments).
Principle of moments
When a body is balanced, the total clockwise moment about a point equals the total anticlockwise moment about the same point.
In order for an object to be in equilibrium (2)
- The resultant force on the object must be zero
2.The resultant moment (about any point) must be zero (the principle of moments).
The turning effect of a force is often referred to as ___________ or torque.
moment
The moment of a force about a point is defined as the force multiplied by the ___________ distance from the point to the line of action of the force.
perpendicular
If the size of the force is increased, then the moment will ___________.
increase
A force may cause a clockwise moment or an __________ moment.
anti-clockwise
The principle of moments can be applied to any object which is in ___________.
equilibrium.
Explain, using your understanding of moments, why it may be easier to use a longer spanner rather than a shorter one to loosen a nut.
With a longer spanner the perpendicular distance from the pivot to the line of action of the force will be greater. This means that for any given force, the moment (turning effect) will be greater.
