1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
sweet [91]
3 years ago
13

You've always wondered about the acceleration of the elevators in the 101 story-tall Empire State Building. One day, while visit

ing New York, you take your bathroom scale into the elevator and stand on them. The scales read 160 lb as the door closes. The reading varies between 130 lb and 180 lb as the elevator travels 101 floors.
a. What is the magnitude of the acceleration as the elevator starts upward?
b. What is the magnitude of the acceleration as the elevator brakes to a stop?
Physics
1 answer:
Arte-miy333 [17]3 years ago
8 0

Answer:

a)  a = 4 ft / s² , b) a = -6 ft / s²

Explanation:

The balance is subjected to two forces: the weight of the person directed downward and the spring reaction directed upward.

When the person rides the elevator, the acceleration is zero

            F - W = 0

            F = W

            F = 160 lb

let's find the mass of the body

            W = mg

            m = W / g

            m = 160/32

           m = 5 slug

A) when the elevator is moving up

            F - W = m a

            F = W + m a

            F - W / m = m a

            F = m (g + a)

therefore the scale reading (F) must be higher, in this case F = 180 lb

             a = F / m - g

            a = 180 - 160)/5

            a = 4 ft / s²

b) when the elevator is stopping

in this case the direction is opposite to the speed, that is to say downwards

              F- W = m (-a)

              a = W - F / m

              a = 130 -160 /5

              a = -6 ft / s²

You might be interested in
How much mass should be attached to a vertical ideal spring having a spring constant (force constant) of 39.5 n/m so that it wil
mrs_skeptik [129]
The frequency of a simple harmonic oscillator such as a spring-mass system is given by
f= \frac{1}{2 \pi}   \sqrt{ \frac{k}{m} }
where 
k is the spring constant
m is the mass attached to the spring.

Re-arranging the formula, we get:
m= \frac{k}{4 \pi^2 f^2}
and since we know the constant of the spring:
k=39.5 N/m
and the frequency of oscillation:
f=1.00 Hz
we can find the value of the mass attached to it:
m= \frac{39.5 Hz}{4 \pi^2 (1.00 Hz)^2} = 1.00 kg
7 0
3 years ago
A motorcycle starts from rest and has a constant acceleration. In a time interval t, it undergoes a displacement x and attains a
iren [92.7K]

Answer:

√(6ax)

Explanation:

Hi!

The question states that during a time t the motorcyle underwent a displacement x at constant acceleration a starting from rest, mathematically we can express it as:

x=(1/2)at^2

Then the we need to find the time t' for which the displacement is 3x

3x=(1/2)a(t')^2

Solving for t':

t'=√(6x/a)

Now, the velocity of the motorcycle as a function of time is:

v(t)=a*t

Evaluating at t=t'

v(t')=a*√(6x/a)=√(6*x*a)

Which is the final velocity

Have a nice day!

3 0
3 years ago
What do zooplankton and krill have in common?
serious [3.7K]
<h2><em>Hello, thank you for choosing brainly today. My name is Ethan and I'll be solving your question. </em><em><u>"What do zooplankton and krill have in common?"</u></em></h2>

Krill and plankton are two groups of organisms found in the ocean. Krill are species of crustacean related to shrimp, and serve as a very important link in the food chain of the sea. Plankton consist of a larger group of organisms with much more variety, including bacteria, algae, protozoans, jellyfish and some species of cephalopods.

Propulsion

The primary factor that determines whether a species is plankton or not is propulsion. Plankton organisms lack the ability to swim against the tide, and instead float from place to place on sea currents. They may be capable of some movement, and some types of plankton can even hunt for food, but none is powerful enough to make its own headway through the ocean. Adult krill are capable of swimming against currents, but their larvae and eggs fall into the plankton category.

Variation

Krill are crustaceans of the Euphausiacea order, which consists of 86 different species. Plankton, on the other hand, can come from a wide variety of different species and orders. Plankton fall into three broad categories, depending on their primary function. Phytoplankton are plant-like organisms, capable of photosynthesis. Zooplankton are animal plankton species that get their nutrients by eating other microscopic organisms. Bacterioplankton are the smallest plankton, and often serve as food for zooplankton and other lifeforms.

Appearance

Krill species have similar characteristics and generally resemble tiny shrimp. Most species reach around 2 centimeters (0.8 inches) as adults, while the largest species can reach sizes of up to 15 centimeters (5.9 inches). Plankton, on the other hand, consists of organisms of many different shapes and sizes. The smallest categories include microscopic viruses, protozoans, small crustaceans, and other tiny organisms. At the larger end of the scale, megaplankton are any plankton over 2 centimeters (0.8 inches) in size, and include large animals, such as cephalopods and jellyfish. The largest plankton is the lion's mane jellyfish, which can reach 2.5 meters (8.2 feet) in diameter and grow tentacles more than 36.5 meters (120 feet) long.

Role

Plankton and krill serve similar, but slightly different, roles in the food chain. Phytoplankton synthesize nutrients, while bacterioplankton recycle nutrients from decomposing matter in the ocean, providing some of the fundamental sources of nutrition for all ocean creatures. Zooplankton serve to concentrate those nutrients by eating smaller plankton and serving as food for larger creatures. Krill are one step up in the food chain, eating plankton and serving as a nutrient bridge from microscopic life forms to larger fish and mammals.

6 0
3 years ago
If an electromagnetic wave has components Ey = E0 sin(kx - ωt) and Bz = B0 sin(kx - ωt), in what direction is it traveling?
fomenos

Answer:

Its traveling in the +x direction

Explanation:

The E-field is in the +y-direction, and the B-field is in the +z-direction, so it must be moving along the +x-direction, since the E-field, B-field and the direction of moving are all at right angles to each other.

8 0
3 years ago
Discuss whether any work is being done by each of the following agents and, if so, whether the work is positive or negative: (a)
Aleks04 [339]

Answer:

a) As the chicken is still, the displacement is zero, which implies that the work is zero.

b) as the person is still there is no displacement therefore the work is zero

c) Lagraua applies a vertical force and the displacement is vertical, therefore the Work is positive

d) the force of gravity is directed downwards and the displacement is upwards, therefore the angle between it is 180º and the 180º fly is -1. Consequently the lock is negative

e) when the person meticulously feels the upward force and the displacement is downward, therefore the work is negative

Explanation:

Work is defined by the expression

        W = F. r

bold letters indicate vectors, we can write this expression as a module

        W= F r cos θ

where is at the angle between force and displacement.

Let's apply this expression to the different cases

a) As the chicken is still, the displacement is zero, which implies that the work is zero.

b) as the person is still there is no displacement therefore the work is zero

c) Lagraua applies a vertical force and the displacement is vertical, therefore the Work is positive

d) the force of gravity is directed downwards and the displacement is upwards, therefore the angle between it is 180º and the 180º fly is -1. Consequently the lock is negative

e) when the person meticulously feels the upward force and the displacement is downward, therefore the work is negative

7 0
3 years ago
Other questions:
  • Suppose you want to make a nested function call (i.e. a call to a function from inside of another function) using a jal rather t
    15·1 answer
  • Protons are released from rest in a Van de Graaff accelerator. They start from a region where the potential is 7.15 MV then trav
    13·1 answer
  • Susan goes out to exercise. She runs for one hour at a constant speed and velocity. What is the overall net force acting on Susa
    10·2 answers
  • Graph y=2 line find value of y when x =5
    12·2 answers
  • Which has greater mass of a bowling ball at rest for a rolling basketball which has greater momentum
    5·1 answer
  • A block of mass M is placed on an inclined surface. The incline makes an angle theta with respect to the horizontal. What are th
    7·1 answer
  • At 10:30 AM, detectives discover a dead body in a room and measure its temperature at 31∘C. One hour later, the body’s temperatu
    10·1 answer
  • When the early universe cooled enough for atoms to form, _____ began.
    10·2 answers
  • Why do I hear a loud sound when I put my ear against the wall and knock
    14·1 answer
  • The temperature of a substance is 45 C. Convert this to Kelvin.
    14·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!