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
lesya [120]
3 years ago
5

A girl wants to count the steps of a moving escalator which is going up. If she counts 60 steps going up and 90 coming down. How

many steps would she have to take in either direction if the escalator were standing still?
Physics
1 answer:
brilliants [131]3 years ago
3 0
Let

V the speed of the girl per step
v the speed of the escalator per step
L the length between ground and floor in number of steps

V*60+v*60=L => V+v=L/60
V*90-v*90=L => V-v=L/90

By adding the equations V+v=L/60 and V-v=L/90 we get:

2V=L(3+2)/180

V=5L/360

V = L/72

Time to climb (in steps) with v=0 (escalator standing still) is:

V*t=L

t = L/V

t = L/(L/72)

t =72 steps

The girl will count 72 steps.
You might be interested in
The sensitivity of a measuring instrument is the value of the smallest quantity that can be read or estimated with it. What is t
nirvana33 [79]

Answer:

The smallest part of a millimeter that can be read with a digital caliper with a four digit display is 0.02mm. Thus, it has to be converted to centimetre. So, divide by 10, we then have 0.02/10= *0.002cm* not mm.

6 0
4 years ago
What does it mean if the moon is waxing and waning
konstantin123 [22]
Both verbs come from Olde English. 
That's why everybody clearly understood their meaning until
a hundred years ago, but nobody understands them now.


"Waxing"  =  growing

For two weeks after the New Moon, it's growing toward Full.
First it's a waxing crescent for a week, then it's waxing gibbous.


"Waning"  =  shrinking

For two weeks after the Full Moon, it's shrinking toward New.
First it's waning gibbous for a week, then it's a waning crescent.
6 0
3 years ago
Establishing a potential difference The deflection plates in an oscilloscope are 10 cm by 2 cm with a gap distance of 1 mm. A 10
11111nata11111 [884]

Answer:

1.62\times 10^{-8}\ \text{s}

Explanation:

\epsilon_0 = Vacuum permittivity = 8.854\times 10^{-12}\ \text{F/m}

A = Area = 10\times 2\times 10^{-4}\ \text{m}^2

d = Distance between plates = 1 mm

V_c = Changed voltage = 60 V

V = Initial voltage = 100 V

R = Resistance = 1000\ \Omega

Capacitance is given by

C=\dfrac{\epsilon_0A}{d}\\\Rightarrow C=\dfrac{8.854\times 10^{-12}\times 10\times 2\times 10^{-4}}{1\times 10^{-3}}\\\Rightarrow C=1.7708\times 10^{-11}\ \text{F}

We have the relation

V_c=V(1-e^{-\dfrac{t}{CR}})\\\Rightarrow e^{-\dfrac{t}{CR}}=1-\dfrac{V_c}{V}\\\Rightarrow -\dfrac{t}{CR}=\ln (1-\dfrac{V_c}{V})\\\Rightarrow t=-CR\ln (1-\dfrac{V_c}{V})\\\Rightarrow t=-1.7708\times 10^{-11}\times 1000\ln(1-\dfrac{60}{100})\\\Rightarrow t=1.62\times 10^{-8}\ \text{s}

The time taken for the potential difference to reach the required level is 1.62\times 10^{-8}\ \text{s}.

5 0
3 years ago
Que hace falta para descubrir hasta que punto todas y todos somos diferentes y ver que eso, más bien es valioso y positivo
lara [203]

Answer:

Para descubrir que las diferencias entre las personas son valiosas y positivas para la creación de sociedades más diversas y enriquecidas culturalmente, es necesario valorar las condiciones personales de cada persona de modo positivo, abandonando posturas discriminatorias como el racismo o la xenofobia, para así aceptar la diversidad social. Además, debe fomentarse el respeto por la opinión y la visión del otro, para que las personas no tomen al que piensa diferente como un adversario al que hay que confrontar. Solo así podrá lograrse una sociedad más diversa y respetuosa de las diferencias, sean culturales, étnicas o intelectuales.

5 0
3 years ago
Is an airplane circling in preparation for a landing potential energy or kinetic energy ?
grin007 [14]
It would be kinetic energy
4 0
3 years ago
Other questions:
  • What properties of sound determine the volume of sound?
    10·1 answer
  • In a physics laboratory experiment, a coil with 200 turns enclosing an area of 11.8 cm^2 is rotated during the time interval 4.9
    8·1 answer
  • Anyone know the answer to this question?
    5·1 answer
  • Help me rearrange this formula. <br><br>I've been trying but I can't remember how to do it.​
    13·1 answer
  • A ball on the end of a rope is moving in a vertical circle near the surface of the earth. Point A is at the top of the circle; C
    10·1 answer
  • Can you find the density of water? How would you do it?
    11·1 answer
  • What is this question
    8·2 answers
  • How did Robert Whittaker change classification?
    12·2 answers
  • Under the influence of its drive force, a snowmobile is moving at a constant velocity along a horizontal patch of snow. When the
    14·1 answer
  • 30 POINTS!
    12·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!