Select the correct answer.

A heat pump absorbs heat from the atmosphere at a rate of 30 kW. If work is being done to run this heat pump at a rate of 7.7 kW

Volgvan

Answer:

Option D 3.9

Explanation:

First, you need to use the correct equation which is the following:

COP = Q/W

Where:

Q = heat absorbed

W = work done by the pump

COP = coefficient of perfomance

We have all the data, so, all you need to do is replace in the above expression and you shoould get the correct result:

COP = 30 / 7.7

COP = 3.896

This result you can round it to 3.9. option D.

8 0

3 years ago

Sometimes a new experimental result may seem to go against a well-established scientific theory. Which statement BEST describes

MrMuchimi

The best thing to do in this case is to redo the experiment and re record the info, it has to be precise and accurate so you also have to check if your procedure is correct. If the results are both accurate and precise then you have to report your findings to the committee of that specific field. <span />

7 0

3 years ago

Read 2 more answers

Mary takes 6.0 seconds to run up a flight of stairs that is 102 meters long. If Mary's weight is 87 newtons, what power has Mary

fredd [130]

Answer: 1479watts

Explanation:

Power is defined as the energy expended or work done in a specific time.

Mathematically,

Power = Workdone/time taken

Since work done is force × distance

Power = force × distance/time

Force = Mary's weight = 87N

Distance = height of the flight = 102meters

Time = 6.0seconds

Substituting in the formula we have;

Power = 87 × 102/6

Power = 1,479watts

Note that the time must be in seconds before usage. If its given in minutes, you will have to convert to seconds

8 0

3 years ago

If the block is subjected to the force of F = 500 N, determine its velocity at s = 0.5 m. When s = 0, the block is at rest and t

STatiana [176]

Answer:

The velocity is $4.6 m/s^2$

Explanation:

Given:

Force = 500N

Distance s= 0

To find :

Its velocity at s = 0.5 m

Solution:

$\sum F_{x}=m a$

$F\left(\frac{4}{5}\right)-F_{S}=13 a$

$500\left(\frac{4}{5}\right)-\left(k_{s}\right)=13 a$

$400-(500 s)=13 a$

$a = \frac{400 -(500s)}{13}$

$a = (30.77 -38.46s) m/s^2$

Using the relation,

$a=\frac{d v}{d t}=\frac{d v}{d s} \times \frac{d s}{d t}$

$a=v \frac{d v}{d s}$

$v d v=a d s$

Now integrating on both sides

$\int_{0}^{v} v d v=\int_{0}^{0.5} a d s$

$\int_{0}^{v} v d v=\int_{0}^{0.5}(30.77-38.46 s) d s$

$\left[\frac{v^{2}}{2}\right]_{0}^{2}=\left[\left(30.77 s-19.23 s^{2}\right)\right]_{0}^{0.5}$

$\left[\frac{v^{2}}{2}\right]=\left[\left(30.77(0.5)-19.23(0.5)^{2}\right)\right]$

$\left[\frac{v^{2}}{2}\right]=[15.385-4.807]$

$\left[\frac{v^{2}}{2}\right]=10.578$

$v^{2}=10.578 \times 2$

$v^{2}=21.15$

$v = \sqrt{21.15}$

$v = 4.6 m/s^2$

8 0

3 years ago

A total resistance of 3.03 Ω is to be produced by connecting an unknown resistance to a 12.18 Ω resistance. (a) What must be the

insens350 [35]

Answer:

(a) 4.0334Ω

(b)parallel

Explanation:

for resistors connected in parallel;

$\frac{1}{R_{eq} } =\frac{1}{R1}+\frac{1}{R2}$

Req =3.03Ω , R1 =12.18Ω

$\frac{1}{3.03 } =\frac{1}{12.18}+\frac{1}{R2}$

$\frac{1}{R2}=\frac{1}{3.03 }-\frac{1}{12.18}$

$\frac{1}{R2}=0.2479$

R2=1/0.2479

R2=4.0334Ω

(b)parallel connection is suitable for the desired total resistance. series connection can not be used to achieve a lower resistance as the equation for series connection is.

Req = R1+R2

3 0

4 years ago