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# CP CALC You are standing on a bathroom scale in an ISBN: 9780321675460 31

## Solution for problem 77P Chapter 5

University Physics | 13th Edition

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Problem 77P

CP CALC ?You are standing on a bathroom scale in an elevator in a tall building. Your mass is 64 kg. The elevator starts from rest and travels upward with a speed that varies with time according to v(t) = (3.0 m/s2)t + (0.20 m/s3)t2. When t = 4.0 s, what is the reading on the bathroom scale?

Step-by-Step Solution:

Solution 77P Step 1: Your mass is 64 kg. The elevator starts accelerating upwards. The velocity as a function of time is given as, 2 v(t) = 3t + 0.20 t ----------------(1) As we know that, acceleration is the time derivative of velocity, so let’s find it. dv d 2 a = dt = dt(3t + 0.20 t ) = 3 + (0.20 × 2) t = 3 + 0.40t St time t = 4 s, the acceleration will be, a = 3 + 0.40 × 4 = 4.6 m/s .2 Step 2: The weight is how much normal reaction an object is getting. To visualize this let’s see the diagram. Here in this figure, a block of mass m is getting the normal reaction of mg. So, it’s weight is mg. Now think of an object in an elevator which is accelerating upwards with an acceleration “a”. The diagram is shown below. The equation for which can be written as, N mg = ma N = mg + ma = m(g + a)------------------(2)

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##### ISBN: 9780321675460

The full step-by-step solution to problem: 77P from chapter: 5 was answered by , our top Physics solution expert on 05/06/17, 06:07PM. This full solution covers the following key subjects: Scale, bathroom, elevator, according, building. This expansive textbook survival guide covers 26 chapters, and 2929 solutions. This textbook survival guide was created for the textbook: University Physics, edition: 13. University Physics was written by and is associated to the ISBN: 9780321675460. Since the solution to 77P from 5 chapter was answered, more than 382 students have viewed the full step-by-step answer. The answer to “CP CALC ?You are standing on a bathroom scale in an elevator in a tall building. Your mass is 64 kg. The elevator starts from rest and travels upward with a speed that varies with time according to v(t) = (3.0 m/s2)t + (0.20 m/s3)t2. When t = 4.0 s, what is the reading on the bathroom scale?” is broken down into a number of easy to follow steps, and 58 words.

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