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3 years ago

Which of the following represents a system that is completely open?

Physics

2 answers:

Bezzdna [24]3 years ago

6 0

Answer:

I choose D

Explanation:

because all of the other ones are most likey to be close/coverd

fredd [130]3 years ago

5 0

The correct answer is D. The system that is completely open of the available answers would be an open pot of boiling water. This is due to the fact that an open system is defined as one in which energy or mass can be put out into or taken from the environment. Therefore, the evaporation of water due to the heat when a pot is boiling would be an example of lost energy, and therefore this is an open system.

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In one cycle, a heat engine takes in 1000 J of heat from a high-temperature reservoir, releases 600 J of heat to a lower-tempera

Talja [164]

Answer:

η = 40 %

Explanation:

Given that

Qa ,Heat addition= 1000 J

Qr,Heat rejection= 600 J

Work done ,W= 400 J

We know that ,efficiency of a engine given as

$\eta=\dfrac{W(net)}{Q(heat\ addition)}$

Now by putting the values in the above equation ,then we get

$\eta=\dfrac{400}{1000}$

η = 0.4

The efficiency in percentage is given as

η = 0.4 x 100 %

η = 40 %

Therefore the answer will be 40%.

4 0

3 years ago

Identify the palindromic base sequence in the DNA donor molecule shown.

Airida [17]

Explanation:

Since a double helix is formed by two paired antiparallel strands of nucleotides that run in opposite directions, and the nucleotides always pair in the same way (adenine (A) with thymine (T) in DNA or uracil (U) in RNA; cytosine (C) with guanine (G)), a (single-stranded) nucleotide sequence is said to be a palindrome

6 0

3 years ago

h(t) = - 16t2 + 64t + 112 where t is the time in seconds. After how many seconds does the arrow reach it maximum height? Round t

laila [671]

Answer:

2 seconds

Explanation:

The function of height is given in form of time. For maximum height, we need to use the concept of maxima and minima of differentiation.

$h(t)=-16t^{2}+64t+112$

Differentiate with respect to t on both the sides, we get

$\frac{dh}{dt}=-32t+64$

For maxima and minima, put the value of dh / dt is equal to zero. we get

- 32 t + 64 = 0

t = 2 second

Thus, the arrow reaches at maximum height after 2 seconds.

8 0

3 years ago

A man strikes one end of a thin rod with a hammer. The speed of sound in the rod is 15 times the speed of sound in air. A woman,

lina2011 [118]

Answer:

44.1 m

Explanation:

Given:

$V_a$ = speed of sound in air = 343 m/s
$V_r$ = speed of sound in the rod = $15V_a$
$\Delta t$ = times interval between the hearing the sound twice = 0.12 s

Assumptions:

$l$ = length of the rod
$t$ = time taken by the sound to travel through the rod
$T$ = time taken by the sound to travel to through air to the same point = $t+\Delta t = t+0.12\ s$

We know that the distance traveled by the sound in a particular medium is equal to the product of the speed of sound in that medium and the time taken.

For traveling sound through the rod, we have

$l=V_r t\\\Rightarrow t = \dfrac{l}{V_r}$ ..........eqn(1)

For traveling sound through the air to the women ear for traveling the same distance, we have

$l=V_aT\\\Rightarrow l=V_a(t+0.12)\\\Rightarrow l=V_a(\dfrac{l}{V_r}+0.12)\,\,\,\,\,\,(\textrm{From eqn (1)})\\\Rightarrow l=V_a(\dfrac{l}{15V_a}+0.12)\\\Rightarrow l=\dfrac{l}{15}+0.12V_a\\\Rightarrow l-\dfrac{l}{15}=0.12V_a\\\Rightarrow \dfrac{14l}{15}=0.12V_a\\\Rightarrow l = \dfrac{15}{14}\times 0.12V_a\\\Rightarrow l = \dfrac{15}{14}\times 0.12\times 343\\\Rightarrow l = \dfrac{15}{14}\times 0.12\times 343\\\Rightarrow l = 44.1\ m$

Hence, the length of the rod is 44.1 m.

4 0

3 years ago

PLEASE help

Natalija [7]

Answer:

Explanation:

initial velocity = 24m/s

final velocity = 0 ( since she is coming to a rest )

time = 12 s

∴ acceleration = final velocity - initial velocity / time

= 0 -24 / 12

= -24/12

= -2 m/s

hope this helps

plz mark it as brainliest

6 0

3 years ago

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