sec 4 science ministry exam

What is permafrost?

Permafrost is a layer of permanently frozen soil.

What is the active layer?

The top layer of permafrost. Melts in the summer.

What are the consequences of permafrost?

-Sinking land

-adds to GHG effect. (Carbon dioxide and methane released)

What is a catchment area?

Natural slope in land and all water drains down into the same place.

Affect Human activity on catchment area?

Human activity doesn’t only affect the general area, but all areas down stream. Example, fertilizer from farm gets into water way, affected lands downstream.

Define salinity?

a measure of quantity of salt in a solution.

How does salinity affect the density of a solution?

More salt-higher salinity-higher density

less salt- lower salinity- lower density.

What is a surface current?

a current that only goes as deep 400m. It is caused by the wind.

What is a subsurface current?

Currents caused by the density of the water. Cold water sinks and hot water rises. This movement creates the currents.

What is thermohaline circulation?

combination of surface/subsurface currents. Functions like a converyer belt which moves warm and cold water around the earth.

What is a glacier?

A mass of ice on land. Formed from packed snow. Made of fresh water.

What is pack ice?

Large slabs of ice floating on the ocean.

Made of brackish water(mix of salt and fresh water).

Only in polar regions

Consequence of glaciers melting

Sea levels rise since they are on land and not in the water.

decreases the ocean salinity.

consequence of melting pack ice

Thermohaline circulation slows down.

decreases the oceans salinity.

What is the greenhouse gas effect?

The trapping of heat in the Earth's atmosphere by greenhouse gases, such as carbon dioxide and methane, leading to global warming.

Why is the GHG effect essential for life on earth?

They keep the planet’s temperature stable.

Why is there a rise in GHG?

Due to a rise in burning of fossil fuels and farming, it releases more GHG’s and the planet is overwhelmed and cannot handle it. This leads the climate change.

What are fossil fuels?

a non-renewable energy source. Produced from burning dead plants and animal residue. This burning releases GHG gasses such as carbon dioxide and methane, intemsifiying the greenhouse gas effect.

What is nuclear energy?

a non-renewable energy source. Radioactive element found in the lithosphere. Highly toxic.

What is geothermal energy?

Renewable energy. From hot magma that releases geothermal energy. low atmospheric pollution.

what is hydroelectric energy?

Renewable energy. produced from falling water. possible flooding. building dams can ruin habitats,

What is the pH scale?

a way of measuring the pH of a solution.

scale runs from 1-14

what is concentration?

a measure of the amount of solute dissolved in a certain amount of solution.

What Is the pH range for an acidic solution?

1-6

What Is the pH range for an basic solution?

8-14

What is the ph for a neutral solution?

7

What is an ion?

An ion is an atom or molecule that has gained or lost electrons, resulting in a positive or negative charge.

How does an aqueous solution conduct electricity?

electrolytic dissolution of a solute, sepereating positive and negative charges. this means they can conduct electricity.

what is rapid conduction?

a form of oxidation. releases a large amount of energy over a short period of time. ex) a candle burning

what is photosynthesis?

production of glucose and oxygen. (plants feeding themself)

carbon dioxide-water-solar energy →glucose -oxygen

what is cellular respiration?

Cellular respiration is the process where cells convert glucose into energy in the form of ATP, using oxygen and producing carbon dioxide as a byproduct.

glucose-oxygen → carbon dioxie-water- energy

what is acid-base neutralization?

combination of an acid and a base to form a salt and water.

How to determine by the written molecular formula is a solution is a basic, acidic, or neutral?

Acids normally start with “H”

Bases normally end in “OH”

Salts will be a combination of metal and nonmetal

what is the law of conservation of mass?

in all chemical reactions, the mass of reactants is equal to the mass of the products.

what are the families of the periodic table?

alkali metals, alkali earth metals, halogens, noble gases.

what are the three types of particles, their charged, and their location?

Proton-positive-nucleus

electron-negative-shells

neutron-neutral-nucleus.

How do electrical charges work?

two objects with similar electrical charges will repel each other (Positive-Positive). Two objects with opposite charges will attract eachother. (positive-negative)

What is ohm’s law?

describes the relationship current intensity, potential difference and resistance.

What is current intensity (I) ?

The amount of charge that flows through point of an electrical circuit in one second.

Whats potential difference (V) ?

the amount of energy provided by the power supply.

What is resistance (R) ?

The ability of a material to resist the flow of electric charges.

What are the equations for ohms law?

v= I x R

I= V/ R

R = V/I

What is a series circuit?

All elements are linked directly together. All charged flow through the same pathways.

What is a parallel circuit?

Elements are not linked. Has at least one branch off. Charges flow through different pathways.

When do you use ammeters?

In series circuts

When do you use voltmeters?

In parallel circuts

What is electrical power?

The amount of work an electrical device can perform in one second.

Formula is P=V I

Further dissect the formula P=VI

P is the electrical energy expressed in Watts

V is the potential difference expressed in volts

I is the current intensity expressed in Amperes

How to calculate electrical energy consunmed, the power of an electrical appliance, and the amount of time it is in operation?

E= P T

E is electrical energy expressed in Joules(J) or Kilowatt hour(kWh)

P is the electrical power expressed in Watts(W) or Kilowatts

T is the time expressed in second (S) or hours (H)

Four basic links in technical objects

direct/indirect

rigid/flexible

removable/non-removable

complete/partial

How to determine if a technical object is direct or indirect?

Direct means that two parts held together without a linking component.

Indirect means that it requires a linking component to be held together.

How to know if an object is rigid or flexible?

rigid means that the linking component is not flexible.

flexible means that the linking component can be deformed and returned to the initial position.

How to know if an object is removable or non-removable?

removable means that the linked parts can be separated without damaging the object.

non-removable means that the linked parts cannot be seperated without damaging.

How to know if an object is complete or partial?

complete means that the linking component prevents the two parts from moving independently

partial means that the linking component allows the two parts to move independently from one another.

What are the three types of guiding control?

Translational, rotational, helical

What Is translational guiding?

the straight translational motion. (Back and forth)

What is rotational guiding?

the rotational moving of a part

what is helical guiding?

the translational motion of a moving part while it rotates around the same axis.

What transmission system is this?

friction gears:

-rotational motion from one gear to another.

-reversible

-easy to assemble

-wheels must always be together

What is this transmission system?

Belt and pulley:

-rotational motion

-reversible

What is this transmission system?

Gear train:

-rotational motion

-reversible

what transmission system is this?

Chain and sprocket:

-rotational motion

-reversible

what transmission system is this?

Worn and worm gear:

-rotational

-non reversible

What transformation is this?

screw gear type 1:

-screw is free

-nut is fixed

-rotational

-ireversible

What transformation is this?

screw gear type 2:

-screw is fixed

-nut is free

-rotational

-ireversible

What transformation is this?

Cam and follower:

-rotational

-irreversible

What transformation is this?

Slider crank:

-rotational motion

-reversible

What transformation is this?

Rack and Pinion:

-rotational

-reversible

Whats a conductor?

A substance that allows current to flow

Whats an insulator?

A substance that does not allow current to flow.

What are the characteristics of a good conductor?

-Large diameter

-short

-cold

-made of copper

Energy transformation in a lightbulb

electrical→light and heat

What can electrical energy be transformed into?

luminous,sound,mechanical,thermal