chapter 5: work, power, and energy chapter 5-1 (p. 168-171) physics
TRANSCRIPT
There are two types of work
1. Everyday sense
“I work at McDonald’s.”
“It is hard work to think this much.”
There are two types of work.2. Scientific sense
Work – a force that causes a change in motion (force across a distance)
Example – pushing a car or riding a bike
Calculating Work
- Work = force applied across a distance
W = F•d•(cos θ)
W = work measured in Joules
F = force measured in Newtons
d = displacement measured in meters
Units of work- Work is measured in Joules (J)
1 Joule = 1 Newton x 1 meter
1 J = work of lifting an apple from your
waist to the top of your head
- The SI units for work are named for James Prescott Joule (1818-1889), a British physicist who did much research in the area of energy
Positive or Negative Work
- Since work is dependent on displacement, and displacement is directional, therefore work is directional.