A __________ is often written as an if/then statement.

Dwayne ‘The Rock’ Johnson needs to escape from the fourth floor of a burning building (in a movie). He ties a rope around his wa

ZanzabumX [31]

Answer:

Final Speed of Dwayne 'The Rock' Johnson = 15.812 m/s

Explanation:

Let's start out with finding the force acting downwards because of the mass of 'The Rock':

Dwayne 'The Rock' Johnson: 118kg x 9.81m/s = 1157.58 N

Now the problem also states that the kinetic friction of the desk in this problem is 370 N

Since the pulley is smooth, the weight of Dwayne Johnson being transferred fully, and pulls the desk with a force of 1157.58 N. The frictional force of the desk is resisting this motion by a force of 370 N. Subtracting both forces we get the resultant force on the desk to be: 1157.58 - 370 = 787.58 N

Now lets use F = ma to calculate for the acceleration of the desk:

787.58 = 63 x acceleration

acceleration = 12.501 m/s

Finally, we can use the motion equation:

$v^2 - u^2 = 2*a*s$

here u = 0 m/s (since initial speed of the desk is 0)

a = 12.501 m/s

and s = 10 m

Solving this we get:

$v^2 - 0 = 2 * 12.501 * 10$

$v = 15.812 m/s$

Since the desk and Mr. Dwayne Johnson are connected by a taught rope, they are travelling at the same speed. Thus, Dwayne also travels at 15.812 m/s when the desk reaches the window.

5 0

3 years ago

Dario, a prep cook at an Italian restaurant, spins a salad spinner and observes that it rotates 20.0 times in 5.00 seconds and t

ziro4ka [17]

Answer:

(a). The acceleration is 8.3 rad/s².

(b). The time is 3.0 sec.

Explanation:

Given that,

Rotation = 20.0 times

Time = 5.00 sec

We need to calculate the angular frequency

Using formula of angular frequency

$\omega_{i}=20\times\dfrac{2\pi}{T}$

put the value into the formula

$\omega_{i}=20\times\dfrac{2\pi}{5.00}$

$\omega_{i}=8.00\pi$

We need to calculate the angular displacement

Using formula of angular displacement

$\theta=6\times2\pi=12\pi$

We need to calculate the angular acceleration

Using equation of angular motion

$\omega_{f}^2-\omega_{i}^2=2\alpha\times\theta$

$0-64\pi^2=2\times12\pi\times\alpha$

$\alpha=-\dfrac{64\pi^2}{24\pi}$

$\alpha=-8.3\ rad/s^2$

Negative sign shows the opposite direction of the motion.

The acceleration is 8.3 rad/s².

We need to calculate the time

Using equation of angular motion

$\omega_{f}-\omega_{i}=\alpha\times t$

$0-8\pi=-8.3t$

$t=\dfrac{8\pi}{8.3}$

$t=3.0\ sec$

The time is 3.0 sec.

Hence, (a). The acceleration is 8.3 rad/s².

(b). The time is 3.0 sec.

4 0

3 years ago

Someone please help. Describe how electric potential energy, kinetic energy, and work change when two charges of opposite sign a

erik [133]

Answer:

The answer is based on the conservation of energy law; something you should really understand by now.

For convenience we can hold one of the two charges still; it becomes the frame of reference. And everything we say is in reference to the designated static charge, call it Q.

So the moving charge, call it q, has total energy TE = PE. It's all potential energy as we start with q not moving.

It has potential energy because in order to separate q from Q, we had to do work, add energy, on q. And from the COE law, that work added is converted into PE.

It's a bit like lifting something off the ground. That's work and it becomes GPE. So there's some work, in separating the two charges in the first place.

But there's more.

Now we let q go. As opposites attract, q is pulled to Q. And that force from Q is working on q, force over distance. Which means the potential energy q started with is being converted into kinetic energy. q is accelerating and picking up speed.

And there's more work, done by the EMF on charge q. That converts the PE into KE and the q charge smashes into Q with some kinetic energy.

5 0

3 years ago

What is the maximum number of lines per centimeter a diffraction grating can have and produce a complete first-order spectrum fo

emmainna [20.7K]

Answer:

14,300 lines per cm

Explanation:

Given that

The wavelength of visible light ranges from 400 nm to 400nm

It is possible to find the maximum number of lines per cm. This maximum number of lines per cm is reciprocal of the least distance separating two adjacent slits, using the following equation.

mλ = dsin (θ), where

m = order of diffraction.

λ = wavelength of the incident light.

d = distance between the centers of the two slits.

θ = angle of diffraction of the mth order.

In order to find the least separation that allows the observation of one complete order of spectrum of the visible region, we make use the maximum or highest wavelength of the visible region that we are given, which is 700 nm.

d = mλ / sin (θ)

Again, we need the distance d to be the smallest, so sin (θ) must be the greatest, and for sin (θ) to be the greatest, it has to be equal to 1. Using the longest wavelength is the best idea because when the smallest wavelength is used the longest wavelength would not be diffracted.

d = mλ / sin (θ)

d = 1 * 700nm / 1

d = 700 nm

Next, we say that

n = 1/d

n = 1 / 700 x

n = 1, 430,000 lines per m, converting to cm, we have n = 14,300 lines per cm

3 0

3 years ago

Glycerin at a temperature of 30 degrees celcius flows at a rate of 8×10−6m3/s through a horizontal tube with a 30mm diameter. wh

MariettaO [177]

The pressure drop in pascal is 3.824*10^4 Pascals.

To find the answer, we need to know about the Poiseuille's formula.

<h3>How to find the pressure drop in pascal?</h3>

We have the Poiseuille's formula,

$Q=\frac{\pi Pr^4}{8\beta l}$

where, Q is the rate of flow, P is the pressure drop, r is the radius of the pipe, $\beta$ is the coefficient of viscosity (0.95Pas-s for Glycerin) and l being the length of the tube.

It is given that,

$Q=8*10^{-6}m^3/s\\diameter=30mm, thus,\\r=15mm\\l=100m\\\beta =0.95$

Thus, the pressure drop will be,

$P=\frac{8Q\beta l}{\pi r^4} =\frac{8*8*10^{-6}*0.95*100}{3.14*(15*10^{-3})^4} \\\\P=3.824*10^4Pascals.$

Thus, we can conclude that, the pressure drop in pascal is 3.824*10^4 Pascals.

Learn more about the Poiseuille's formula here:

brainly.com/question/13180459

#SPJ4

3 0

1 year ago