In our study of energy and work, we have yet to address the time it takes to transfer energy from one system to another. This rate is called power, and given symbol P (upper case, we’ll use the lower-case p for another variable later). Since the rate is time based, the equation for power is:
P = Δ E/ Δ t
The units for power from this equation would be J/s, which physicists shortened to Watt, with the symbol W (upper-case since it’s named after a person, James Watt). So…
1 J / s = 1 W
Contents of this post
Class practice
Work your way through Problem 5.12 on Page 143.
Class and homework
Page 154, problems 48, 50, 51, 53, 54
Book resources
Section 5.6: Power, pages 142-146
Some power trivia
- The most powerful production car (not specially built or modified) is the Bugatti’s 8.0-litre W16 in the Chiron. Four turbos help this car mill 1,479hp (1.2MW) through its 8.0-litre quad-turbo W16 engine, producing a massive 187.5 horsepower per liter. It’s mass is 2,000 kg.
- The most powerful pickup truck is the 2019 Ford Super Duty (F250 and F350). Ford’s 6.7-liter diesel V8 delivers 450 horsepower (336 kW); more than any other truck in this class. The mass of this truck is 3,500 kg.