Class Management Help Homework 10 Begin Date: 11/6/2017 4:00:00 PM-Due Date: 11/

Question

Class Management Help Homework 10 Begin Date: 11/6/2017 4:00:00 PM-Due Date: 11/9/2017 11:59:00 PM End Date: 11/13/2017 11:59:00 PM (17%) Problem 3: Suppose a car travels 102 km at a speed of 30.5 m/s, and uses 1.8 gal of gasoline in the process. Only 30% of the gasoline goes into useful work to keep the car moving at a constant speed. In this problem you may assume that I gallon of gasoline produces 1.2 x 108 J of energy. 50% Part (a) what is the force exerted, in newtons, to keep the car moving at constant speed? F=11 Grade Summ Deductions Potential tan7 Submissions Attempts rema sin0 cos0 | 4 | 5 | 6 cotan asin0 acos0 atan0 acotan0 sinh per attemp 2 3 detailed view coshO tanh cotanh0 0 O Degrees O Radians VO give up Submit Hint Feedback

Explanation / Answer

ANSWER:-

Given

speed = 30.5 m/s and 1.6 gal of gasoline is used and distance (d) = 102 km

Wf = 1.8 * (1.2 *108 J/gal) (0.30) = 0.648 * 108 = 6.48 * 107 J

Now to keep the car moving at constant speed Work done by friction is given by

Wf = Ff * d

Ff = Wf /d

= 6.48 * 107 J / 102 * 103 m

= 0.0635 * 104 N

= 635 N

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