## Understanding Physics Units in Basic Form

Published: July 2, 2024

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### How much is m/s^2

- It means we have an increase in speed of 1m/s in 1 second.
- For 10m/s^2 for 60 seconds means
- Speed of an object increases by 10 m/s every second for a duration of 60 seconds.
- In the end, the object will have a speed of 600m/s.

- Acceleration due to gravity on earth in 9.8m/s^2
- It means if you’re falling from a height, your speed will increase by 9.8m/s every second.
- If one fall from building from 1 km height, when you reach the ground, you will have a speed of 98m/s.
- For comparison, Usain Bolt’s top speed is ~10m/s.

### How much is 1 Newton

- 1N is the force required to accelerate a 1kg mass at 1m/s^2.
- For 60kg of human, the force applied on Earth is approximately 588.6 N
- 60kg * 9.8m/s^2 = 588.6N

### How much is 1 Joule

- Amount of energy to move 1kg mass at 1m/s^2 for 1 m distance.
- Picking up 100 gm apple from ground to table(at 1m height) is ~1J of work.
- 0.1kg * 9.8m/s^2 * 1m = 0.98J

### How much is 1 Watt

- Amount of power needed to move 1kg mass at 1m/s^2 for 1 m distance in 1 second.
*Same apple example, if you pick up 100 gm apple from ground to table(at 1m height) in 2 second then*- Joule =
`0.1kg * 9.8m/s^2 * 1m = 0.98J`

- Watt =
`0.98J / 2(second) = 0.49W`

**It means you need 0.49W power to pick up apple in 2 seconds at 1m height.**

- Joule =
- For 100W light bulb,
- Power = 100W == 100J/s
- Time = 2 hour
- Energy = 100W * 2h == 200Wh

### What is Watt-hour

- Watt-hour is the unit of energy?
- 1 watt-hour is equal to 1 watt of power sustained for 1 hour (1 Wh = 1 W × 1 h = 3600 joules).
- 100-watt light bulb
- Time = 2 hour
- Energy =
`100W * 1h = 100Wh = 0.1KWh`

- For AC with with 2000Wh
- Time = 1 hour
- Power = 2000W
- Energy =
`2000W * 1h = 2000Wh = 2KWh = 2 units`

### What is kilowatt-hour

- 1 Kwh is 1000 watt-hour.
- Commonly used unit of energy for electricity, also called “unit” in India.
- For AC with 2 Kwh, it means 2000W power sustained for 1 hour.
- For every hour, it consumes 2 Kwh of energy.

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