Physics, 09.12.2020 06:40 LolaSalem

400 N pushes on a 25-kg box. Starting from rest, the box achieves a velocity of 2.0 m/s in a time of 4.0 s. Find the coefficient of kinetic friction between box and
floor.

400 N pushes on a 25-kg box. Starting from rest, the box achieves

a velocity of 2.0 m/s in a time

Answers: 2

Show answers

Answers

Answer from: dbn4everloved8

The kinetic coefficient of friction between box and floor is 0.443.

Explanation:

Let suppose that the box is accelerated uniformly, the acceleration (), measured in meters per square second, is determined by the following kinematic formula:

$a = \frac{v_{f}-v_{o}}{t}$ (1)

Where:

$v_{o}$ , $v_{f}$ - Initial and final speeds of the box, measured in meters per second.

- Time, measured in seconds.

If we know that $v_{o} = 0\,\frac{m}{s}$ , $v_{f} = 2\,\frac{m}{s}$ and $t = 4\,s$ , then the acceleration experimented by the box is:

$a = \frac{2\,\frac{m}{s}-0\,\frac{m}{s} }{4\,s}$

$a = 0.5\,\frac{m}{s^{2}}$

Based on the body diagram, we proceed to form the equations of equilibrium:

$\Sigma F_{x} = P\cdot \cos \theta -\mu_{k}\cdot N = m\cdot a$ (1)

$\Sigma F_{y} = N - m\cdot g - P\cdot \sin \theta = 0$ (2)

Where:

- Magnitude of the force exerted on the box, measured in newtons.

$\theta$ - Direction of the force exerted on the box, measured in sexagesimal degrees.

$\mu_{k}$ - Kinetic coefficient of friction between box and floor, dimensionless.

- Normal force from the floor to the box, measured in newtons.

- Mass of the block, measured in kilograms.

- Gravitational acceleration, measured in meters per square second.

Now we proceed to solve the system of equation for the kinetic coefficient of friction between box and floor:

By (1)

$\mu_{k}\cdot N = P\cdot \cos \theta -m\cdot a$

$\mu_{k} = \frac{P\cdot \cos \theta - m\cdot a}{N}$

By (2)

$N = m\cdot g +P\cdot \sin \theta$

And then, we get the resulting expression:

$\mu_{k} = \frac{P\cdot \cos \theta - m\cdot a}{m\cdot g + P\cdot \sin \theta}$ (3)

If we know that $P = 400\,N$ , $\theta = 50^{\circ}$ , $m = 25\,kg$ , $g = 9.807\,\frac{m}{s^{2}}$ and $a = 0.5\,\frac{m}{s^{2}}$ , then the kinetic coefficient of friction between box and floor is:

$\mu_{k} = \frac{(400\,N)\cdot \cos 50^{\circ}-(25\,kg)\cdot \left(0.5\,\frac{m}{s^{2}} \right)}{(25\,kg)\cdot \left(9.807\,\frac{m}{s^{2}} \right)+(400\,N)\cdot \sin 50^{\circ}}$

$\mu_{k} = 0.443$

The kinetic coefficient of friction between box and floor is 0.443.

Answer from: Quest

nec chapter 5 contains

c. information on special occupancy areas

nec chapter 6 covers

a. special equipment

which of the following rules contain the words shall or shall not and must be adhered to?

b. mandatory rules

which of the following rules identify actions that are allowed but not required and typically cover options or alternative methods?

c. optional rules

which of the following serves as the introduction to the nec and provides an overview of the book?

a. nec article 90

organizations that test products for safety are

c. nrtls

the nec is published by the

a national fire protection association

the nec is divided into

b. 9 chapters

the nec provides informative annexes for

c. informational materials and examples

two terms from nec article 100 that trainees should become familiar with are

b. labeled and listed

explanation:

Answer from: Quest

Alinear relationship would look like a straight line on the graph. it could have a positive negative or 0 slope. so it could be a line potentially going in any direction but it must be perfectly straight.

Another question on Physics

Physics, 22.06.2019 00:30

Comedians like to joke that the reason we havenâ€™t been visited by intelligent life from elsewhere in the universe is that aliens have been monitoring earthâ€™s broadcasts of intellectually embarrassing tv programs, like gilliganâ€™s island, fear factor, the jersey shore, and the jerry springer showand so consider us far too primitive to merit a visit. letâ€™s check the assertion that aliens could have been receiving them. tv programs are broadcast at a frequency of about 100mhz with about 100kw of total power in 30frames per second, which emanatesroughly uniformly in all directions. assume that interstellar space transmits these broadcasts without attenuation. no matter how smart they are, aliens would require at least one photon per frame to interpret our signals. findthe number of photons per unit time per unit area reaching a receiver on a possible planet in the nearest star system, which is about 4 light-years away (a light-year is the distance light travels in a year). if aliens aimed a receiver or detector directly at earth, how big (in diameter) would it have to be to receive a photon per frame

Answers: 2

Answer

Physics, 22.06.2019 10:00

** urgent** the voltage across the primary winding is 350,000 v, and the voltage across the secondary winding is 17,500 v. if the secondary winding has 600 coils, how many coils are in the primary winding? a- 30 coilsb- 583 coilsc- 12,000 coilsd- 332,500 coils

Answers: 1

Answer

Physics, 22.06.2019 11:30

1. a camcorder has a power rating of 19 watts. if the output voltage from its battery is 7 volts, what current does it use?answer units 2. a 1.5m wire carries a 6 a current when a potential difference of 57 v is applied. what is the resistance of the wire? your

Answers: 2

Answer

Physics, 22.06.2019 15:00

What pressure difference is required between the ends of a 2.0-m-long, 1.0-mm-diameter horizontal tube for 40 c water to flow through it at an average speed of 4.0 m/s?

Answers: 1

Answer

You know the right answer?

400 N pushes on a 25-kg box. Starting from rest, the box achieves a velocity of 2.0 m/s in a time o...

Questions