DLISC1 - wk10-11

Question 1

what is physics?

Answer 1

it is the study of various physical phenomena nad the fundemental laws governing it

Question 2

basic things of nature

Answer 2

force
motion
matter
light
sound
heat
electricity
magnetism

Question 3

what are the three types of natural phenomena

Answer 3

• Physical: formation of rainbow, formation of clouds
• Chemical: conversion of wood into ash, rusting of iron
• Biological: pumping of blood by heart, exchange of gases through lungs

Question 4

what is classical physics

Answer 4

• developed before 19th century
  includes
  classical mechanics
  wave mechanics
  thermodynamics
  electromagnetism
  optics

Question 5

what is modern physics

Answer 5

• developed after 19th century
  includes
  atomic physics
  nuclear physics
  quantim mechanics

Question 6

what occupations use physics?

Answer 6

biologists
chemists
astronomers
civil engineers
mechanical engineers
electrical engineers
electronic engineers

Question 7

what are basic quantities?

Answer 7

physical quantity that cannot be defined in any other physical quantity.
- length
- mass
- time
- temperature
- electric current

Question 8

what are derived quantities? (ants)

Answer 8

physical quantities which are obtained fomr the base quantites using time or divide
- area
- volume
- speed
- force

Ants Vacationing Seek Fun

Question 9

what are scalars (Monkeys)

Answer 9

is a physical quantity that is completely described by its magnitude
- mass
- length
- speed
- distance
- power
- time

Monkeys Love Salsa, Dancing Past Turtles.

Question 10

what are vectors?

Answer 10

an object that has a magnitude and a direction
- displacement
- velocity
- acceleration
- friction

Question 11

what are Newtons 3 lawys of motion

Answer 11

1. An object in motion tends to stay in motion and an object at rest tends to stay at rest unless acted upon by an unbalanced force. (law of inertia)
2. Force equals mass times acceleration (F = ma)
   acceleration = a measurement of how quickly an object is changing speed
3. For every action there is an equal and opposite reaction. (action-reaction)

Question 12

what is it meant by an unbalanced and balanced force?

Answer 12

If the forces on an object are equal and opposite, they are said to be balances, and an object experiences no change in motion.

If they are not equal and opposite, then the forces are unbalanced and the motion of the object changes.

Question 13

what is electricity

Answer 13

the movement of electrons between atoms

Question 14

what is static electricity

Answer 14

• The build-up of an electric charge on the surface of an object
• The charge builds up but does not flow
• Static electricity is potential energy. It does not move. It is stored

Question 15

what is static discharge?

Answer 15

Occurs when there is a loss of static electricity due to three possible things:
- Friction: rubbing
- Conduction: direct contact
- Induction: through an electrical field, not direct contact

Question 16

what are electricity currents

Answer 16

• The flow of electrons from one place to another
• Measured in amperes

Question 17

how can we control currents?

Answer 17

• by electricity circuits
• circuit: is a path of the flow of electrons
• we use wires

Question 18

2 types of currents

Answer 18

• Direct current (DC) – where electrons flow in the same direction in a wire
• Alternating current (AC) – electrons flow in different directions in a wire

Question 19

2 types of circuits

Answer 19

• Series circuit: the components are lined up along one path. If the circuit is broken, all components turn off
• Parallel circuit: there are several branching paths to the components. If the circuit is broken at any one branch, only the components on that branch will turn off.

Question 20

what are conductors and insulators?

Answer 20

conductors: material thorugh which electric current flows easily
- metal
- water
insulators: materials which electric current cannot move
- rubber
- plastic
- paper

Question 21

what is resistance?

Answer 21

• The opposition to the flow of an electric current, producing heat.
• The greater the resistance, the less current gets through.
• Good conductors have low resistance.
• Measured in ohms.

Question 22

what infleunces resistance?

Answer 22

• Material of wire – aluminium and copper have low resistance
• Thickness – the thicker the wire the lower the resistance
• Length – shorter wire has lower resistance
• Temperature – lower temperature has lower resistance

Question 23

what is voltage?

Answer 23

• The measure of energy given to the charge flowing in a circuit
• The greater the voltage, the greater the force or “pressure” that drives the charge through the circuit

Question 24

what is Ohm’s law?

Answer 24

ohms law defines the correlation between electric current (I), voltage (V) and resistance (R) in a conductor.
can be expressed as V x I x R
- resistacne = voltage/current
- ohms = volts/amps

Question 25

what are the three primary electrical parameters?

Answer 25

1. the volt - the pressure that is put on free electrons that causes them to flow 2. the ampere - defines the flow of electric current 3. the ohm - the unit of resistance in a conductor - determined by: size, material and temperature

Question 26

magnets have two poles, what are they

Answer 26

norht pole south pole

Question 27

magnetic poles always exist between magnets

Answer 27

1. Like poles repel (south-south, or north-north) 2. Opposite oles attract (south-north)

Question 28

magnetic poles always occur in pairs

Answer 28

1. Magnetics poles can never be isolate 2. If you break a magnet, each piece will have a north and a south pole

Question 29

what are magnetic fields

Answer 29

A region in which a magnetic force can be detected. Direction of a magnetic field is the direction in which the north pole of a compass needle points at that location.

Question 30

what are kinematics?

Answer 30

- Is the branch of mechanics that describe the motion of objects, without considering the forces causing the motion - It deals with concepts such as position, velocity, acceleration and time and how these quantities are related to each other

Question 30

what are dynamics?

Answer 30

- Dynamics is the branch of mechanics that deals with the causes of motion, specifically the forces that cause objects to move - It involves studying how forces affect the motions of objects, how they interact with each other, and how they cause objects to accelerate

Question 31

what is energy, kinetic energy and potential energy

Answer 31

energy: the capacity or power to do work by the application of force kinetic energy: is the energy possessed by an object due to its motion potential energy: the energy stored in an object due to its position

Question 32

examples of potential energy

Answer 32

- Apples on a tree - Water stored in a dam - Compressed spring - Stretched rubber band - Crossbow

Question 33

examples of kinetic energy

Answer 33

- Rotating fan - Car in motion - Man surfing - Boy playing football - High speed train

Question 34

components of motion

Answer 34

- Position (where you are or were) - Speed/velocity – how position changes over time (in metres/second, m/s) - Acceleration – how your velocity changes over time (in meters/second squared) - Time – how long you were moving (in seconds, s) - Distance/displacement) – how far you have moved (in meters, m)

Question 35

what is the fluid flow?

Answer 35

- A fluid is a substance in the liquid or gas phase - The fluid flow is the movement of a fluid in a certain direction 1. The layers 2. The streamline 3. The density

Question 36

two types of fluid flow

Answer 36

steady (laminar) flow turbulent flow

Question 37

internal vs external flow

Answer 37

External: the flow of an unbounded fluid over a surface such as a plate, wire or a pipe. Internal: the flow in a pipe or duct if the fluid is completely bounded by solid surfaces.

Question 38

what is bernoulli's principle

Answer 38

1. Conservation law of energy 2. The relation between velocity and pressure

Question 39

what is bernoulli's equation

Answer 39

Energy per unit volume before = energy per unit volume after

Question 40

what happens when the velocity of a flow inside the tube increases?

Answer 40

The pressure inside the tube decreases gradually, by increasing the velocity and vice versa. Increase in the speed of the fluid occurs simultaneously with a decrease in the fluids potential energy.