#63. thank you! Section 6.7 Power is making homemade ice cream. She exerts a for

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#63. thank you!

Section 6.7 Power is making homemade ice cream. She exerts a force of A Nn the free end of the crank handle on the ice-cream magnitu rhis end moves on a circular path of radius 0.28 m. The applied parallel to the motion of the handle. If the med once every 1.3 s, what is the average power being handle is turned expended? ever ssm Bicyclists in the Tour de France do enormous amounts of work during a race. For example, the average power per kilogram generated by seven-time-winner Lance Armstrong (m 75.0kg) 72. is 6.50 W per kilogram of his body mass. (a) How much work does plac he do during a 135-km race in which his average speed is 12.0 m/s? wor b) Often, the work done is expressed in nutritional Calories rather than rele in joules. Express the work done in part (a) in terms of nutritional Calories, noting that 1 joule 2.389 x 10-4 nutritional Calories. G You are working out on a rowing machine. Each time you pull the rowing bar (which simulates the oars) toward you, it in a time of 1.5 s. The readout on the display 64. moves a distance of 1.2 m indicates that the averag e power you are producing is 82 W. What is the magnitude of the force that you exert on the handle? mlmh A car accelerates uniformly from rest to 20.0 m/s in 5.6 s along

Explanation / Answer

Distance travelled d = 135 km = 135000 m

Speed = 12 m/s

Time taken = d/s = 135000/12 = 11250 seconds

Now work = power * time

Work = 6.5 x 75 x 11250 = 5.48 MJ

Now 1 J = 2.389 x 10-4 Nutritional calories

5.48 MJ = 5.48 x 106 x 2.389 x10-4 = 1309.17 Nutritional Calories.

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