Grade 9 Natural Sciences (NS) Summaries - Term 3 (Via Afrika): These summaries are compiled using the Via Afrika textbook's Term 3 content. The summaries are in English, with additional notes provided by the compiler.
Strand 3 - Energy and change
Topic 1: Forces
Topic 2: ...
, Environmental cost of The cost of power consumption
electric power • Energy measured in joules (J), not watts (W).
• Electrical appliances rated in watts.
• 80% of electricity produced in coal-fired power • Power refers to the rate of electrical energy
stations releases 900g CO2 and 8g SO2. supply.
• Savings include turning off lights when not in use, • Cranes have varying power consumption times.
keeping fridge door closed, minimizing heater use, • One kilowatt equals 1000 W.
and not using hot water taps when cold.
• Sharing hot water baths, replacing incandescent T7: Cost of
bulbs with compact fluorescents, and turning off
computers and TVs can also reduce costs. electrical Paying for electricity
power • Electricity Meters and Cost Calculation:
Sample
o Every home has a meter to measure energy usage.
o Two types of meters: monthly meters charged by
Alternative energy in municipality or Eskom, and prepaid meters.
the home o Energy is measured in kWh, the unit kilowatt hour.
o Consumer cost is calculated by power rating x time x
• Geysers: Primary energy source, rated at 3,000W, with thermostat for temperature unit price.
Summaries after sample
control.
• Solar geysers: Commonly used for hot water during sunshine.
• Electric geysers: Operate when hot water in solar tank is insufficient or sunlight is scarce.
• Work by absorbing heat, heating water, and circulating it via a pipe.
o Example: 230V, 2,000W electric heater for 3 hours
each evening in June.
Electric appliances
• Cost = power rating x time x unit price = R225,00.
• Electric appliances use current heating effect, electric motors, or
combinations of both.
• Power rating - found on appliances or their packaging.
• Some appliances operate at various power ratings - fan with
three speeds or heater with heat settings.
•
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller SummariesSA. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $6.83. You're not tied to anything after your purchase.
