Heat and temperature | MariyamQureshi | Live - Free Printable

Let's go through the worksheet "Heat and Temperature" step by step and solve each question with clear explanations.

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1. Fill in the blanks:

a) What units are used to measure heat energy?
✔ Joules (J)
> Heat energy is a form of energy, and the standard unit for energy in the metric system is the joule (J).

b) What units are used for temperature?
✔ Degrees Celsius (°C)
> Temperature is measured in degrees Celsius (°C), Kelvin (K), or Fahrenheit (°F). In science, especially at this level, degrees Celsius is commonly used.

c) What instrument do we use for measuring temperature?
✔ Thermometer
> A thermometer is the tool used to measure temperature.

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2. Look at the diagrams and tick the one in each pair that has the most heat energy. Explain your answers.

#### a)
- Large bowl of porridge at 30°C
- Small bowl of porridge at 30°C

✔ Tick the large bowl.

> Explanation: Both bowls are at the same temperature (30°C), but the large bowl has more mass, so it contains more particles. Even though the temperature is the same, the total heat energy depends on mass, temperature, and material. Since both are the same substance (porridge) and at the same temperature, the larger amount has more total heat energy.

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#### b)
- Small pan of soup at 80°C
- Same size pan of soup at 50°C

✔ Tick the small pan at 80°C.

> Explanation: The pans are the same size (same mass), and both contain soup (same material), but the one at 80°C is hotter. Higher temperature means the particles have more kinetic energy. So, even though the mass is the same, the higher temperature means more heat energy.

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3. Look at these two bowls of food:

- 300g soup at 80°C
- 300g ice cream at 2°C
- Air temperature = 20°C

#### a) Will heat flow into the soup or out of it?
✔ Heat will flow OUT of the soup.

> Explanation: The soup is at 80°C, which is hotter than the surrounding air (20°C). Heat flows from hotter to colder objects. So, heat will flow from the soup to the air until they reach thermal equilibrium.

#### b) Will heat flow into the ice cream or out of it?
✔ Heat will flow INTO the ice cream.

> Explanation: The ice cream is at 2°C, which is colder than the surrounding air (20°C). So, heat will flow from the warmer air into the colder ice cream, causing it to warm up.

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4. Think of a situation at home where heat energy is being transferred. Draw a picture and add arrows to show the direction of heat flow.

> ✔ Example Situation: A cup of hot tea cooling down on a table.

Description:
- A cup of hot tea (say, 70°C) is placed on a table at room temperature (20°C).
- Heat flows from the hot tea to the cooler surroundings (air and table).

Drawing Description (since you can't draw here):
- Draw a cup labeled "Hot Tea".
- Draw an arrow pointing outward from the cup to the air around it.
- Label the arrow: "Heat energy flowing out".
- Optionally, draw the table beneath and another small arrow from the cup to the table.

> 🔁 Remember: Heat always flows from hotter to colder.

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✔ Summary of Key Concepts:

| Concept | Explanation |
|--------|-------------|
| Heat Energy | Measured in joules (J); depends on mass, temperature, and material. |
| Temperature | Measured in °C; indicates how hot something is. |
| Thermometer | Instrument to measure temperature. |
| Heat Flow | Always moves from hotter to colder objects. |

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✔ Final Answers Recap:

1.
a) Joules
b) Degrees Celsius
c) Thermometer

2.
a) Large bowl – more mass → more heat energy
b) Pan at 80°C – higher temperature → more heat energy

3.
a) Heat flows out of soup → it's hotter than air
b) Heat flows into ice cream → it's colder than air

4. Example: Hot coffee cooling on a table → heat flows from coffee to air and table.

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Let me know if you'd like a printable version or want help drawing the diagram!