Question

(a) How long will the energy in a 122 kcal cup of yogurt last in a woman doing work at the rate of 145 W with an efficiency of 20% (such as in leisurely climbing stairs)? min (b) Does the time found in part (a) imply that it is easy to consume more food calories than you can reasonably expect to work off with exercise? Yes No

          (a) How long will the energy in a 122 kcal cup of yogurt last in a woman doing work at the rate of 145 W with an efficiency of 20% (such as in leisurely climbing stairs)?
min
(b) Does the time found in part (a) imply that it is easy to consume more food calories than you can reasonably expect to work off with exercise?
Yes
No

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(a) How long will the energy in a 122 kcal cup of yogurt last in a woman doing work at the rate of 145 W with an efficiency of 20% (such as in leisurely climbing stairs)?
min
(b) Does the time found in part (a) imply that it is easy to consume more food calories than you can reasonably expect to work off with exercise?
Yes
No

Added by Hunter M.

College Physics for AP® Courses

Irina Lyublinskaya, Gregg Wolfe, Douglas…

Chapter 15

Instant Answer

Solved by Expert Eduard Sanchez

04/23/2022

Step 1

Given work rate = 145 W Efficiency = 20% = 0.2 Total power = Work rate / Efficiency = 145 W / 0.2 = 725 W Show more…

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(a) How long will the energy in a 122 kcal cup of yogurt last in a woman doing work at the rate of 145 W with an efficiency of 20% (such as in leisurely climbing stairs)? min (b) Does the time found in part (a) imply that it is easy to consume more food calories than you can reasonably expect to work off with exercise? Yes No

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Transcript

0:00 Hi there.

00:01 So for this problem for part a, we are asked about how long will the energy? so the energy is given that is equal to 122 kilojoules.

00:18 That and well, kilocalories, sorry, kilocalories.

00:25 And cup of yogurt less in a woman doing work at a rate.

00:31 So the work is given, that work done.

00:39 Let's set that is the power out work is equal to 145 watts with an efficiency.

00:54 And efficiency is 20%.

01:00 That is the same as 0 .2.

01:03 So with that said, the first thing that we need to determine is the total power.

01:10 And the total power is just simply the value given for the workout, which is 145 watts, divided by the efficiency, which is 0 .2.

01:23 So from this, we obtain a value of 7205 watts.

01:36 Now, we know that the power is the energy divided by the time.

01:41 So since we are given the time and the power, we just need to simply solve for the time because the question is how long.

01:49 That means that we need to determine the time.

01:51 So that will be the energy that we are given divided by the power.

01:56 However, the energy should be in joules.

02:00 So what we need to do is first to transform the value that we are given, that is 122 kilo calories.

02:09 Kilo means stems to the three calories...

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