Joules to Watt-seconds conversion

How to convert joules to watt-seconds?

Joules (J) and watt-seconds (W·s) are units of energy. They are actually equivalent, so the conversion between them is straightforward:

1 Joule (J) = 1 Watt-second (W·s).

This is because a watt is defined as one joule per second. So, when you measure energy in joules, you're effectively already using watt-seconds.

Real-World Examples of Joules

1. Lifting an Object:

   • Lifting a small apple (approximately 100 grams) to a height of 1 meter requires about 1 Joule of energy.

2. Lighting a Small LED:

   • A small LED light (about 1-watt power) running for 1 second consumes 1 Joule of energy.

3. Boiling Water:

   • To boil 1 gram of water from 0°C to 100°C, it takes about 418 Joules of energy (considering specific heat capacity of water is about 4.18 J/g°C).

4. Running a Marathon:

   • A typical marathon runner might expend around 360,000 Joules (or 360 kJ) during the run.

5. Household Electricity:

   • A 100-watt light bulb turned on for 1 hour consumes 360,000 Joules (or 360 kJ) of energy.
     • Calculation: $\text{Power} \times \text{Time} = \text{Energy}$
     • Where Power (P) = 100 W and Time (t) = 3600 seconds (1 hour)
     • So, $100 \text{ W} \times 3600 \text{ s} = 360,000 \text{ J}$

6. Kinetic Energy:

   • A car (mass = 1000 kg) moving at a speed of 20 m/s has a kinetic energy of 200,000 Joules.
     • Calculation: $\text{KE} = \frac{1}{2} m v^2$
     • Where mass (m) = 1000 kg and velocity (v) = 20 m/s
     • So, $\text{KE} = \frac{1}{2} \times 1000 \text{ kg} \times (20 \text{ m/s})^2 = 200,000 \text{ J}$

Understanding how energy is expressed in different units and examples helps illustrate how much energy different activities and processes require.