A 2.0 kg block rests on a level surface. The coefficient of static friction is, and the coefficient of kinetic friction is A horizontal force, X, is applied to the block. As X is increased, the block begins moving. Describe how the force of friction varies as X increases from the moment the block is at rest to when it begins moving. Indicate how you could determine the force of friction at each value of X―before the block starts moving, at the point it starts moving, and after it is moving. Show your work.

ps. I had to change F to X because of brainly.

By Newton's second law, the net force acting on the block in the vertical direction is

∑ F [ver] = n - mg = 0

where n = magnitude of normal force and mg = weight of the block. It follows that n = mg.

When the block is at rest, the applied force X will not be enough to move the box until it can overcome the maximum mag. of static friction. If µ[s] is the coefficient of static friction, then the maximum mag. of the frictional force is

f = µ[s] n = µ[s] mg

The net horizontal force would be

∑ F [hor] = X - µ[s] mg = 0

so a minimum force of X = µ[s] mg is required to get the block moving. Any mag. smaller than this and the block stays at rest/in equilibrium.

Once the mag. of X exceeds µ[s] mg, the block will begin to move. At that point, if the coefficient of kinetic friction is µ[k], then the net force on the block is

∑ F [hor] = X - µ[k] mg = 0

so a minimum force of X = µ[k] mg would be needed to keep the block moving at constant speed, or otherwise X = µ[k] mg + ma if the block is accelerating with mag. a.

The principles here are captured in the attached plot.

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John throws a ball with a velocity of 30 m/s at an angle of 60 degrees. What is the horizontal component of the velocity?

a 30 m/s
b 0 m/s
c 25.9 m/s
d 15 m/s

Read the excerpt from The Building of Manhattan.

A temporary, small narrow-gauge track system was installed on each floor as it was needed. This enabled the material to be moved from the truck at ground level onto dump carts, raised by elevator to the designated floor, wheeled onto the track, and moved quickly to the exact spot needed. Turntables built into the track allowed the carts to be shifted about in any direction.

Which question can be answered only if an illustration accompanies the text?

What did turntables built into the track allow?
How were dump carts raised to designated floors?
When was a track system installed on a floor?
What does a turntable built into a track loo

HELP!!!!
Which statement describes earthquakes?

They release energy.
They are caused by reduced stress in rocks.
They begin at the epicenter.
They result from movement on Earth’s surface.

HELP ME IM NOT GOOD THAT THIS :))))

Someone plz give me some boy advice I really need it.

Rafiq has heard that continued exposure to light for 10 days can change the colour of some blue dyes used to colour cotton clothing. He decides to test this. He takes a piece of clothing dyed with a blue dye which is suspected to lose colour on such exposure. He cuts the cloth into two pieces.
Which experiment is likely to help him conclude if the dye indeed can change colour?
He should expose, for 10 days-

A. Both pieces under 2 identical lamps.
B. One piece under a lamp; keep the other in darkness.
C. One piece for 5 days and one for 10 days under identical lamps
D. One piece folded and one piece spread out under 2 identical lamps.

Can someone please give me the (Answers) to this? ... please ...

A pitcher throws a softball toward home plate. When the ball hits the catcher’s mitt, its horizontal velocity is 32 meters/second. The softball’s velocity goes to 0 meters/second in 0. 8 seconds when caught. If the softball has a mass of 0. 2 kilograms, what’s the force of the impact? Use F = ma, where. The force of the impact is newtons.

Two billiard balls move toward each other on a table. The mass of the number three ball, m1, is 5 g with a velocity of 3 m/s. The mass of the eight ball, m2, is 6 g with a velocity of 1 m/s. After the balls collide, they bounce off each other. The number three ball moves off with a velocity of 5 m/s. What is the final velocity and direction of the eight ball? 8. 6 m/s 5. 7 m/s â€"5. 7 m/s â€"8. 6 m/s.

If the action force is the swimmer pushing water in the leftward direction, what is the reaction force?

PLEASE ANSWER
CORRECTLY PLS

plssss helppppppppppp i need it

A textbook is sitting at rest on a desk. Compared to the magnitude of the force of the textbook on the desk, how
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o less
O zero
O more
O equal

PLZ HELP ME FAST A relationship between two variables is called:
A.
observable
.B.
correlation
.C.
causation
D.
finite.

Help me as soon as possible <3​

the system shown above is released from rest. if friction is negligible, the acceleration of the 4.0 kg block sliding on the table shown above is most nearly

Pleaseeeee HELPPPP THIS IS TIMED ALSO,
A book slides along a table and comes to a stop. Explain, in detail, all the forces acting on the book.

if a big person and a small person run up the stairs at the same time who has more force

if 9 joules of energy are expended pushing on one coulomb of charge round a circuit, what is the emf across the circuit?

Which of the balls will exert the greatest force on object A?Why?

The magnetic field 0. 02 m from a wire is 0. 1 T. What is the magnitude of the magnetic field 0. 01 m from the same wire? 0. 01 T 0. 05 T 0. 1 T 0. 2 T.

how are mass, distance and gpe related

yes that.
Read the excerpt below and then answer the question that follows:
The Book of Dragons
Chapter III The Deliverers of Their Country, an excerpt
By E. Nesbit

It all began with Effie's getting something in her eye. It hurt very much indeed, and it felt something like a red-hot spark—only it seemed to have legs as well, and wings like a fly. Effie rubbed and cried—not real crying, but the kind your eye does all by itself without your being miserable inside your mind—and then she went to her father to have the thing in her eye taken out. Effie's father was a doctor, so of course he knew how to take things out of eyes.

When he had gotten the thing out, he said: "This is very curious." Effie had often got things in her eye before, and her father had always seemed to think it was natural—rather tiresome and naughty perhaps, but still natural. He had never before thought it curious.

Effie stood holding her handkerchief to her eye, and said: "I don't believe it's out." People always say this when they have had something in their eyes.

"Oh, yes—it's out," said the doctor. "Here it is, on the brush. This is very interesting."

Effie had never heard her father say that about anything that she had any share in. She said: "What?"

The doctor carried the brush very carefully across the room, and held the point of it under his microscope—then he twisted the brass screws of the microscope, and looked through the top with one eye.

"Dear me," he said. "Dear, dear me! Four well-developed limbs; a long caudal appendage; five toes, unequal in lengths, almost like one of the Lacertidae, yet there are traces of wings." The creature under his eye wriggled a little in the castor oil, and he went on: "Yes; a bat-like wing. A new specimen, undoubtedly. Effie, run round to the professor and ask him to be kind enough to step in for a few minutes."

"You might give me sixpence, Daddy," said Effie, "because I did bring you the new specimen. I took great care of it inside my eye, and my eye does hurt."

The doctor was so pleased with the new specimen that he gave Effie a shilling, and presently the professor stepped round. He stayed to lunch, and he and the doctor quarreled very happily all the afternoon about the name and the family of the thing that had come out of Effie's eye.

But at teatime another thing happened. Effie's brother Harry fished something out of his tea, which he thought at first was an earwig. He was just getting ready to drop it on the floor, and end its life in the usual way, when it shook itself in the spoon—spread two wet wings, and flopped onto the tablecloth. There it sat, stroking itself with its feet and stretching its wings, and Harry said: "Why, it's a tiny newt!"

The professor leaned forward before the doctor could say a word. "I'll give you half a crown for it, Harry, my lad," he said, speaking very fast; and then he picked it up carefully on his handkerchief.

"It is a new specimen," he said, "and finer than yours, Doctor."

It was a tiny lizard, about half an inch long—with scales and wings.

So now the doctor and the professor each had a specimen, and they were both very pleased. But before long these specimens began to seem less valuable. For the next morning, when the knife-boy was cleaning the doctor's boots, he suddenly dropped the brushes and the boot and the blacking, and screamed out that he was burnt.

And from inside the boot came crawling a lizard as big as a kitten, with large, shiny wings.

"Why," said Effie, "I know what it is. It is a dragon like the one St. George killed."

And Effie was right. That afternoon Towser was bitten in the garden by a dragon about the size of a rabbit, which he had tried to chase, and the next morning all the papers were full of the wonderful "winged lizards" that were appearing all over the country. The papers would not call them dragons, because, of course, no one believes in dragons nowadays—and at any rate the papers were not going to be so silly as to believe in fairy stories. At first there were only a few, but in a week or two the country was simply running alive with dragons of all sizes, and in the air you could sometimes see them as thick as a swarm of bees. They all looked alike except as to size. They were green with scales, and they had four legs and a long tail and great wings like bats' wings, only the wings were a pale, half-transparent yellow, like the gear-boxes on bicycles.

Based on the rising action in the bolded paragraphs, what do we know about Daddy? (5 points)

He is calm and curious.
He is angry and upset.
He is hysterical.
He is uninterested and bored.

HELPPP PLEASE
1) if the distance between two masses are 15 meters and the masses are 350kg and 492 kg
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What is the kinetic energy of a toy truck with a mass of 0. 75 kg and a velocity of 4 m/s? (Formula: ) 3 J 6 J 12 J 24 J.

I have two questions. I hope anyone can help me <3 Question 8 & Question 9. ​

Two gravitational forces act on a
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what equation do you use to calculate force from work to distance