Solution Found!
Suppose a car travels 108 km at a speed of 30.0 m/s, and
Chapter 7, Problem 4(choose chapter or problem)
Suppose a car travels \(108 \mathrm{~km}\) at a speed of \(30.0 \mathrm{~m} / \mathrm{s}\), and uses \(2.0 \text { gal }\) of gasoline. Only \(30 \%\) of the gasoline goes into useful work by the force that keeps the car moving at constant speed despite friction. (See Table \(7.1\) for the energy content of gasoline.)
(a) What is the magnitude of the force exerted to keep the car moving at constant speed?
(b) If the required force is directly proportional to speed, how many gallons will be used to drive \(108 \mathrm{~km}\) at a speed of \(28.0 \mathrm{~m} / \mathrm{s}\)?
Equation Transcription:
Text Transcription:
100 km
30.0 m/s
2.0 gal
30%
7.1
108 km
28.0 m/s
Questions & Answers
QUESTION:
Suppose a car travels \(108 \mathrm{~km}\) at a speed of \(30.0 \mathrm{~m} / \mathrm{s}\), and uses \(2.0 \text { gal }\) of gasoline. Only \(30 \%\) of the gasoline goes into useful work by the force that keeps the car moving at constant speed despite friction. (See Table \(7.1\) for the energy content of gasoline.)
(a) What is the magnitude of the force exerted to keep the car moving at constant speed?
(b) If the required force is directly proportional to speed, how many gallons will be used to drive \(108 \mathrm{~km}\) at a speed of \(28.0 \mathrm{~m} / \mathrm{s}\)?
Equation Transcription:
Text Transcription:
100 km
30.0 m/s
2.0 gal
30%
7.1
108 km
28.0 m/s
ANSWER:
Solution
Step 1
From the friction force in the engine of the car keeps the car moving at 30% of gasoline. We have to find the force that keeps the car speed at constant.