Grade 9 Power Problems (Watts/kWh, power rating question)

In summary, the conversation is about learning how to solve questions involving power rating and energy using given triangles. The person is struggling with missing triangles and converting units. They attempted to solve a problem involving a hot plate with a power rating of 1250 Watts, and determined that the energy used in Kilowatt-hours is 3.75 kWh. However, they are unsure if this is the correct answer and need help converting it to joules.
  • #1
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Homework Statement



So, i need to learn how to do questions with finding out the power rating, and energy etc etc from using the triangles given and i am having some trouble since some of my triangles are missing and i need some help with converting.


Homework Equations



1) A hot plate has a power rating of 1250 Watts. How much energy in Kilowatt-hours is used when this hot plate is used for 3.00 hours at a banquet?


The Attempt at a Solution



I converted the watts to kWh so i turned 1250 to 1.25. On the triangle with the variables of "P," "E," and "T," it says E=Pt So i did 1.25*3 and got 3.75kWh.
The problem is that i thought that "E" was always in joules or Kilojoules so i do not think the answer can be 3.75kWh since that is the power rating.
If i am correct, i need help with converting the 3.75kWh into joules if that is what i need to do.

Thanks !
 
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  • #2
1 Watt = 1 Joule/second
1 Watt*hour = (1 Joule/second)*3600 seconds = 3600 Joules
1 kWh = 1000 Watt*hour

Got it?
 

1. What is the difference between watts and kilowatt-hours (kWh)?

Watts (W) and kilowatt-hours (kWh) are units used to measure different aspects of power. Watts refer to the rate at which energy is being used or produced, while kilowatt-hours refer to the amount of energy used or produced over a period of time. In simpler terms, watts measure power, while kilowatt-hours measure energy.

2. How do I calculate the power rating of a device?

The power rating of a device can be calculated by dividing the amount of energy used (in kWh) by the time it took to use that energy (in hours). This will give you the power rating in watts (W). For example, if a device used 1 kWh of energy in 2 hours, its power rating would be 500 watts (1 kWh / 2 hours = 500 watts).

3. Why is it important to know the power rating of a device?

Knowing the power rating of a device is important because it can help you determine how much energy the device will use over time. This can be useful for budgeting and understanding the potential environmental impact of using that device. It can also help you choose the right size or type of device for your needs.

4. What is the difference between power and energy?

Power and energy are often used interchangeably, but they are actually different concepts. Power refers to the rate at which energy is being used or produced, while energy is the actual amount of work being done. Think of it like a car driving at a certain speed (power) versus the distance it travels (energy).

5. How can I reduce my energy consumption to save money?

There are several ways to reduce your energy consumption and save money. This can include turning off lights and electronics when not in use, using energy-efficient appliances, and adjusting your thermostat to conserve energy. It can also be helpful to track your energy usage and make small changes to your daily habits to reduce unnecessary energy consumption.

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