Calorimetry is a cool way to learn about energy changes while doing physical activities. It helps us see how our bodies use energy during exercise. Let's explore how we can use calorimetry to check energy changes in the gym.

What is Calorimetry?

Calorimetry is all about measuring heat. In physical education, we focus on how much energy we use when doing exercises like running, cycling, or lifting weights. By looking at this energy, we can see how effective our workouts are.

How to Use Calorimetry

1. Pick an Activity: For example, let’s measure energy changes while running for 30 minutes.

2. Measure Temperature Change: Use a calorimeter, which is a tool that tracks temperature. Before you run, check the starting temperature of a water sample. After your run, check the temperature again.

3. Calculate Energy Change: We can find out how much heat energy was used or gained with this formula: $Q = mc\Delta T$ Here’s what the letters mean:

   • $Q$ = heat energy (in joules)
   • $m$ = weight of the water (in grams)
   • $c$ = how much heat water can hold (about $4.18 \, \text{J/g°C}$)
   • $\Delta T$ = change in temperature (final temperature minus starting temperature)

Example

Let’s say you have 200 grams of water, and its temperature goes from 20°C to 30°C.

• $m = 200 \, g$
• $\Delta T = 30 - 20 = 10 \, °C$

Now, if we plug these numbers into the formula, we get: $Q = 200 \times 4.18 \times 10 = 8360 \, J$

This shows that your body used about 8360 joules during that run! Knowing how much energy you spend helps you improve your workouts and recover better afterwards.