You walk into an elevator, step onto a scale, and push the 'up' button. You recall that your normal weight is 625 N. Draw a free-body diagram. (b) If you hold a 3.85-kg package by a light vertical string, what will be the tension in this string when the elevator accelerates as in part (a)?

Video transcript

Welcome back everybody. We have a girl who is standing on a scale in an elevator. The girl is also holding package. I'm gonna actually bring this package off to the side so that we can we can analyze it here. Right? So this package is hanging from a string and it has a certain tension on it as the elevator is moving upwards. So it has some tea right? Also acting on it however, is going to be you wait due to gravity which is just MG. And we are told that the elevator is moving upwards with an acceleration of three m per second squared. And we want to figure out what the tension is. But we're going to use Newton's second law here that states that the sum of all forces in the direction we're going to look at the Y direction here equal to mass times some vertical acceleration component plugging into values we have that are tension minus our weight, Mass times gravity, which is going to be four times 9.8 is equal to our mass times are vertical acceleration component, adding four times 9.8 to both sides. We get that our tension equal to four times three plus four times 9.8. Which when you plug into your calculator, you get a final answer of 51.2 Newtons corresponding to answer choice B. Thank you all so much for watching. Hope this video helped. We will see you all in the next one