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3 years ago

Static Friction

Physics

1 answer:

kkurt [141]3 years ago

3 0

Name the element and explain why it is unusual:
a)A liquid metal
b)A non-metal that conducts electricity

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A power plant running at 39 % efficiency generates 330 MW of electric power. Part A At what rate (in MW) is heat energy exhauste

marusya05 [52]

516.154 megawatts of heat are <em>exhausted</em> to the river that cools the plant.

By definition of energy efficiency, we derive an expression for the energy rate exhausted to the river ( $Q_{out}$ ), in megawatts:

$Q_{out} = Q_{in} - W$

$Q_{out} = \left(\frac{1}{\eta}-1 \right)\cdot W$ (1)

Where:

$\eta$ - Efficiency.
$W$ - Electric power, in megawatts.

If we know that $\eta = 0.39$ and $W = 330\,MW$ , then the energy rate exhausted to the river is:

$Q_{out} = \left(\frac{1}{0.39}-1 \right)\cdot (330\,MW)$

$Q_{out} = 516.154\,MW$

516.154 megawatts of heat are <em>exhausted</em> to the river that cools the plant.

We kindly to check this question on first law of thermodynamics: brainly.com/question/3808473

7 0

3 years ago

At what point does the external energy enter the system?

Phoenix [80]

The correct answer as the first one above !

8 0

3 years ago

Before a star is born, the matter that will become the star exists as a

vazorg [7]

Answer:

The answer is D

Explanation:

I'm too lz to explain everything.

sorry.

6 0

3 years ago

Read 2 more answers

Please need help fast

iVinArrow [24]

(a) See graph in attachment

The appropriate graph to draw in this part is a graph of velocity vs time.

In this problem, we have a horse that accelerates from 0 m/s to 15 m/s in 10 s.

Assuming the acceleration of the horse is uniform, it means that the velocity (y-coordinate of the graph) must increase linearly with the time: therefore, the velocity-time graph will appear as a straight line, having the final point at

t = 10 s

v = 15 m/s

(b) $1.5 m/s^2$

The average acceleration of the horse can be calculated as:

$a=\frac{v-u}{t}$

where

v is the final velocity

u is the initial velocity

t is the time interval

In this problem,

u = 0

v = 15 m/s

t = 10 s

Substituting,

$a=\frac{15-0}{10}=1.5 m/s^2$

(c) 75 m

For a uniformly accelerated motion, the distance travelled can be calculated by using the suvat equation:

$s=ut+\frac{1}{2}at^2$

where

s is the distance travelled

u is the initial velocity

t is the time interval

a is the acceleration

In this problem,

u = 0

t = 10 s

$a=1.5 m/s^2$

Substituting,

$s=0+\frac{1}{2}(1.5)(10)^2=75 m$

(d) See attached graphs

In a uniformly accelerated motion:

- The distance travelled (x) follows the equation mentioned in part c,

$x=ut+\frac{1}{2}at^2$

So, we see that this has the form of a parabola: therefore, the graph x vs t will represents a parabola.

- The acceleration is constant during the motion, and its value is

$a=1.5 m/s^2$ (calculated in part b)

therefore, the graph acceleration vs time will show a flat line at a constant value of 1.5 m/s^2.

6 0

3 years ago

Based on The MOHS hardness Scale, which mineral could be scratched by a penny but not by a fingernail

melomori [17]

The correct answer is B. Calcite

Explanation:

Mohs hardness scale indicates the hardness of minerals using a scale from 1 to 10 as well as defining the objects or tools that can be used to scratch the minerals. These two features of minerals are shown in the table of the image. About this, it is shown gypsum and talc can be scratched by just a fingernail, considering minerals with a hardness of 2.5 or below can be scratched by a fingernail. In the case of calcite that has a hardness of 3, this cannot be scratched by a fingernail, but it can be scratched by a penny, which works for minerals with a hardness of 3.5 or below. Thus, the correct answer is Calcite.

6 0

3 years ago