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nirvana33 [79]
3 years ago
10

On an essentially frictionless, horizontal ice rink, a skater moving at 5.0 m/s encounters a rough patch that reduces her speed

by 40 % due to a friction force that is 22 % of her weight. Use the work-energy theorem to find the length of this rough patch. Express your answer using two significant figures.
Physics
1 answer:
Leviafan [203]3 years ago
3 0

Answer:  the length of the rough patch is 4.9 m.

Explanation:

The work - energy theorem, in simple words, expresses that the change in the kinetic energy in an object, is equal to the work done on the object by non-conservative forces, like frictional ones.

In the question, we know that the skater is moving at a given speed, and due to the effects of friction, her speed is reduced to 40%.

Added to this, we are told that the friction force is equal to 22% of her weight so we can write the following:

Ff = 0.22 m. g.

Now the work done by this force, is equal to the product of the force times the distance during which the force acted, i.e,. the distance that we are looking for.

So, we can write the following in a brief:

ΔK = Wf ⇒ 1/2 m (vf² - v₀²) = -Ff . x

(The negative sign explains that the friction force always opposes to the relative movement between the two surfaces in contact).

Replacing by the values, and solving for x, we get:

1/2 ( 2² - 5²) = -0.22. 9.8. x   ⇒  x = 4.9 m

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kipiarov [429]
It is because both of them are attracted towards earth where the heavier body gravity field influence is more in comparision to small. For eg; there are two magnet with less power in besides of huge power or magnetic influence then both of the less power magnet are attracted towards the huge one rather than attracting themselves.


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6 0
3 years ago
Chemicals in the air can combine with rain to produce acid rain, which is harmful to the environment. Which of these is most lik
irinina [24]
Hi there!

Normal rain has a pH between 5.0 and 5.5, which is slightly acidic on the pH scale. Acid rain on the other hand has an average pH of 4.0, much more acidic than your average rain.

Therefore, the most likely pH of acid rain would be 4.0.
7 0
2 years ago
What are the variables of Boyle's law?
vesna_86 [32]

Answer: pressure and volume

Explanation:

Boyle's law states that the volume of a fixed mass of gas is inversely proportional to the pressure of the gas provided temperature is kept constant.

Mathematically, Boyle's law can be explained as: PV = k,

where P is pressure

V is volume, and

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So, increase in the pressure of a gas leads to decrease in its volume and vice versa.

3 0
3 years ago
In a mail-sorting facility, a 2.50-kg package slides down an inclined plane that makes an angle of 20.0° with the horizontal. Th
lawyer [7]

Answer:

The coefficient of kinetic friction is 0.382.

Explanation:

Given:

Angle of inclination is, \theta=20.0°

Mass of package is, m=2.50\ kg

Initial speed of package is, u=2.00\ m/s

Final speed of the package at the bottom is, v=0\ m/s

Distance of travel along the incline is, d=12.0\ m

Acceleration due to gravity is, g=9.8\ m/s^2

Let the coefficient of kinetic friction be \mu.

Now, the frictional force will be acting along the incline but in the direction opposite to the direction of motion.

So, the net acceleration acting on the package will be up the incline and is equal to:

a=\mu g\cos\theta-g\sin\theta ----------------- 1

Now, using equation of motion, we have:

v^2-u^2=2ad\\\\0-(2.00)^2=2a(12.0)

Solving for 'a', we get:

-4.00=24.0a\\\\a=-\frac{4}{24}=-\frac{1}{6}\ m/s^2

Now, plug in the value of 'a' in equation (1). This gives,

\mu g\cos\theta-g\sin\theta=\frac{1}{6} ( Neglecting negative sign)

Plug in all the given values and solve for \mu. This gives,

9.8(-sin(20)+\mu cos(20))=\frac{1}{6}\\\\-0.342+\mu\times 0.94=0.017\\\\0.94\mu=0.342+0.017\\\\0.94\mu=0.359\\\\\mu=\frac{0.359}{0.94}=0.382

Therefore, the coefficient of kinetic friction is 0.382.

5 0
3 years ago
Will give correct answer brainliest
sineoko [7]

200 \times 80\%

<h2><em>calculate</em></h2>

<em>200 \times  \frac{80}{100}</em>

<h2><em>reduce </em><em>the </em><em>numbers</em></h2>

<em>2 \times 80</em>

<h2><em>multiply</em></h2>

<em>= 160</em>

<h2><em>there </em><em>for </em><em>we </em><em>have </em><em>a </em><em>solution</em><em> to</em><em> the</em><em> </em><em>equation</em></h2>

<em>hope </em><em>it</em><em> helps</em>

<em>#</em><em>c</em><em>a</em><em>r</em><em>r</em><em>y</em><em> </em><em>on</em><em> learning</em>

<em>mark </em><em>me</em><em> as</em><em> brainlist</em><em> plss</em>

6 0
3 years ago
Read 2 more answers
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