## Glossary of Work and Power 2

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- What is the formula for a joule?
- A joule equals one newton x one meter

(N x m)

- What is the result of a force moving an object over a distance?
- Work

- What are you doing when you push, lift, or throw and object?
- Work

- What is the formula for work?
- W = F x D

- What is "F" ?
- F = force acting on an object

- What is "d"?
- d = distance the object moves in the direction of the force

- What is the unit of measurement for work in the metric system?
- Joule

- A joule equals the force of what?
- A newton moving an object 1 meter

- Who is the joule named after?
- James Prescott Joule

19th century English physicist who studied transformation

- What is the work done when a 500-N student climbs a rope for 5 meters?
- W = F x D

W = 500n x 5m

W = 2500 x m

W = 2500J

- Is a horse doing work when it stands with a rider sitting on it?
- No - because the horse is not pushing, lifting, or throwing. No force is acting over a distance.

- When you climb to the top of rope and hang there, are you doing work?
- No - not moving your body over a distance

- What is the amount of work done during a given period of time
- Power

- How is power measured?
- Power is measured in watts (W)

- A watt is equal to how many joule?
- 1 W = joule per second

(J/s)

- How many joules is a 100W lightbulb using?
- 100 joules per second

- A kilowatt (kW) is equal to how many watts?
- 1 kW = 1000 W

- One horsepower is equal to how many watts?
- 1 hp = 0.746W

- Horsepower is used to describe what?
- The power of engines

- Who described the power of a steam engine?
- James Watt

A Scottish engineer described the power used to a horse to pull a heavy load

- What is the equation of power?
- Power = Work/Time

P = w/t

- What is the power of a motor that does 2000 J of work in a 10 second period?
- P = w/t

P = 2000J/10s

P = 200J/S

P = 200W

- If the power of a motor is 200W, what is the horsepower of the motor?
- 200W / 746W = .26hp

- Is throwing a football 20 yards work or not?
- Yes

- You push against a wall until you are tired. Is this work?
- No

- Your study these flashcards all day long for this stupid test. Is this work?
- No

- You push your brother out of your way to sit down - are you working?
- Yes

- How much work is done when a 175 N man pulls a sled 500m?
- W = F x D

W = 175 x 500

W = 87,500J

- A 98 N woman carries her baby 12 m. How much work is done?
- No work

- What is the work done when a 1000-N person jumps 1 meter into the air?
- W = F x D

W = 1000 N x 1m

W = 1000 x m

W = 1000J

- A 100W lightbulb has more what than a 60W bulb?

a. power

b. joule

c. watt

d. force - Power

- What is the amount of work per unit of time?
- Power

- What is the reate at which work is done?
- Power

- When power increases, does the rate of work increase or decrease
- Increase

- How much work does a 150w lightbulb do?
- 150 joules

- Power is force x distance and divided by what?
- Time

- When time and force remain the same, power is increased when what increases?
- Distance

- What is the equation for power?
- P = Work/Time

- Power is measured in what?
- watts

- One horsepower equals how many watts?
- 746 watts

- A pencil sharpener uses 1,000 joules in 10 seconds. What is the power usage?
- P = 1,000j /10s

P = 100j / s

P = 100W