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LenKa [72]
3 years ago
13

An escalator is 18.3 m long. If a person stands on the escalator, it takes 47.8 s to ride from the bottom to the top. If a perso

n walks up the moving escalator with a speed of 0.521 m/s relative to the escalator, how long does it take the person to get to the top?
Physics
1 answer:
Novay_Z [31]3 years ago
8 0

Answer:

20.243 s

Explanation:

Because the escalator and person moving in the same direction, relative velocity can be calculated by summing the velocity of the escalator and velocity of the person.  

The speed of escalator can be calculated as,

v_{escalator}=\frac{x}{t}=\frac{18.3}{47.8}=0.383\ m/s

Relative velocity

v_{relative}=v_{escalator}+v_{person}\\\\v_{relative}=0.383+0.521=0.904\ m/s\\

Therefore total time required to take the person to get to the top

t=\frac{x}{v_{relative}}= \frac{18.3}{0.904}=20.243\ s

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3 years ago
The diffusion rate for a solute is 4.0 x 10^-11 kg/s in a solvent- filled channel that has a cross-sectional area of 0.50 cm^2 a
zlopas [31]

Answer:

s = 9.6\times 10^{-12}kg/s

Explanation:

Given:

Solute Diffusion rate  = 4.0 × 10⁻¹¹ kg/s

Area of cross-section = 0.50 cm²

Length of channel  =0.25 cm

Now for the new channel

Area of cross-section = 0.30 cm²

Length of channel  =0.10 cm

let the Solute Diffusion rate  of new channel = s

now equating the diffusion rate per unit volume for both the channels

\frac{4\times 10^{-11}}{0.50\times 0.25}=\frac{s}{0.30\times 0.10}

thus,

s = 9.6\times 10^{-12}kg/s

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3 years ago
Where will water evaporate from?
Elodia [21]

Water will evaporate from any water source and life forms. The answer is letter C. An application of heat into water will cause the water to evaporate. This is because the intermolecular forces of attraction of water can be broken by sufficient energy application.

3 0
3 years ago
Severus Snape knows that density of his powder is 3.00 g/cm3 . He also knows he needs 3.00 cm3 of this powder. What mass in gram
harina [27]

Answer:

He requires 1 gram of mass.

Explanation:

The density is defined as:

\rho = \frac{m}{V}  (1)

Where m is the mass and V is the volume.

Then, m can be isolated from equation 1 in order to determine the mass.

m = \rho \cdot V (2)

m = (3.00g/cm^{3})(3.00cm^{3})  

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Hence, he requires 1 gram of mass.

8 0
3 years ago
A steel ball rolls with a constant velocity on a tabletop 0.950 m high it rolls off and hit the ground 0.352 m from the edge of
sp2606 [1]

Answer:

0.799 m/s if air resistance is negligible.

Explanation:

For how long is the ball in the air?

Acceleration is constant. The change in the ball's height \Delta h depends on the square of the time:

\displaystyle \Delta h = \frac{1}{2} \;g\cdot t^{2} + v_0\cdot t,

where

  • \Delta h is the change in the ball's height.
  • g is the acceleration due to gravity.
  • t is the time for which the ball is in the air.
  • v_0 is the initial vertical velocity of the ball.
  • The height of the ball decreases, so this value should be the opposite of the height of the table relative to the ground. \Delta h = -0.950\;\text{m}.
  • Gravity pulls objects toward the earth, so g is also negative. g \approx -9.81\;\text{m}\cdot\text{s}^{-2} near the surface of the earth.
  • Assume that the table is flat. The vertical velocity of the ball will be zero until it falls off the edge. As a result, v_0 = 0.

Solve for t.

\displaystyle \Delta h = \frac{1}{2} \;g\cdot t^{2} + v_0\cdot t;

\displaystyle -0.950 = \frac{1}{2} \times (-9.81) \cdot t^{2};

\displaystyle t^{2} =\frac{-0.950}{1/2 \times (-9.81)};

t \approx 0.440315\;\text{s}.

What's the initial horizontal velocity of the ball?

  • Horizontal displacement of the ball: \Delta x = 0.352\;\text{m};
  • Time taken: \Delta t = 0.440315\;\text{s}

Assume that air resistance is negligible. Only gravity is acting on the ball when it falls from the tabletop. The horizontal velocity of the ball will not change while the ball is in the air. In other words, the ball will move away from the table at the same speed at which it rolls towards the edge.

\begin{aligned}\text{Rolling Velocity}&=\text{Horizontal Velocity} \\&= \text{Average Horizontal Velocity}\\ &=\frac{\Delta x}{\Delta t}=\frac{0.352\;\text{m}}{0.440315\;\text{s}}=0.0799\;\text{m}\cdot\text{s}^{-1}\end{aligned}.

Both values from the question come with 3 significant figures. Keep more significant figures than that during the calculation and round the final result to the same number of significant figures.

3 0
3 years ago
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