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3 years ago

Which evidence did Ottowa scientists collect in researching PCB concentrations in Alaska?

Physics

2 answers:

Sergio [31]3 years ago

7 0

PCBs were found in greater concentrations in lakes where more salmon spawned.

Olin [163]3 years ago

3 0

Hey mate!
You stuck?

The answer is C) PCBs were found in greater concentrations in lakes where more salmon spawned. Evidence of hti swas depicted in the Ottowa notes of travel.

Hope this helps! :)

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An 80.0-kg object is falling and experiences a drag force due to air resistance. The magnitude of this drag force depends on its

FromTheMoon [43]

Answer:

The terminal speed of this object is 12.6 m/s

Explanation:

It is given that,

Mass of the object, m = 80 kg

The magnitude of drag force is,

$F_{drag}=12v+4v^2$

The terminal speed of an object is attained when the gravitational force is balanced by the gravitational force.

$F_{drag}=mg$

$12v+4v^2=80\times 9.8$

$4v^2+12v=784$

On solving the above quadratic equation, we get two values of v as :

v = 12.58 m/s

v = -15.58 m/s (not possible)

So, the terminal speed of this object is 12.6 m/s. Hence, this is the required solution.

6 0

3 years ago

A 62.0-kg skier is moving at 6.30 m/s on a frictionless, horizontal, snow-covered plateau when she encounters a rough patch 4.90

Klio2033 [76]

Here are the missing questions:
(a) How fast is the skier moving when she gets to the bottom of the hill?
(b) How much internal energy was generated in crossing the rough patch?
Part A
The initial kinetic energy of the skier is:
$E_{k0}=m\frac{v_0^2}{2}$
Part of this energy is then used to do work against the force of friction. Force of friction on the horizontal surface can be calculated using following formula:
$F_f=mg\mu$
The work is simply the force times the length:
$W_f=F_f\cdot L=mg\mu L$
So when the skier passes over the rough patch its energy is:
$E=E_{k0}-W_f$
When the skier is going down the skill gravitational potential energy is transformed into the kinetic energy:
$E_p=E_{k1}\\ mgh=E_{k1}$
So the final energy of the skier is:
$E_f=E_{k0}-W_f+E_{k1}\\ E_f=m\frac{v_0^2}{2}-mg\mu L+mgh=1856.86$J$
This energy is the kinetic energy of the skier:
$E_f=m\frac{v_f^2}{2}\\ v_f=\sqrt{\frac{2E_f}{m}}=7.74\frac{m}{s}$
Part B
We know that skier lost some of its kinetic energy when crossing over the rough patch. This energy is equal to the work done by the skier against the force of friction.
$E_{int}=W_f\\
E_{int}=mg\mu L=894.1$J$

4 0

4 years ago

Which source of power can reduce emission of carbon dioxide?

ki77a [65]

Answer:

wind

Explanation:

this is because the others when burnt releases large amounts of carbon of carbon dioxide as they are carbon based and oxidises when burnt. However wind is renewable and converts the kinetic energy in the wind to electrical energy by the use of a turbine

6 0

3 years ago

Work out the current through an electric heater with a power of 1.38kW if it uses the 230V mains supply.

love history [14]

Answer:

I = 6 A

Explanation:

Given that,

Power of an electric heatr, P = 1.38 kW

The voltage of the mains supply, V = 230 V

We need to find the current through the heater. The electric power in terms of voltage and current is given by :

$P=V\times I\\\\I=\dfrac{P}{V}\\\\I=\dfrac{1.38\times 10^3}{230}\\\\I=6\ A$

So, the current through an electric heater is 6 A.

5 0

3 years ago

April stands on a flat surface . If she has a mass of 72 what is the nirmal force acting on her

gayaneshka [121]

The normal force acting on April as she stands on a flat surface is 705.6 N.

Normal force of the girl

Fₙ = mg

where;

Fₙ is the normal force of the girl
m is mass of the girl
g is acceleration due to gravity

Fₙ = 72 x 9.8

Fₙ = 705.6 N

Thus, the normal force acting on April as she stands on a flat surface is 705.6 N.

Learn more about normal force here: brainly.com/question/14486416

#SPJ1

7 0

2 years ago