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3 years ago

How much heat is needed to raise the temperature of 2 kg of copper from 20º to 30ºC. The specific heat of copper is 390 J/kgºC.

Physics

1 answer:

ryzh [129]3 years ago

3 0

Answer:

7800 J

Explanation:

Heat needed = mass of copper x specific heat of copper x change in temperature

Change in temperature = 30ºC - 20ºC = 10ºC

Specific heat of copper = 390 J/kgºC

Mass of copper = 2 Kg

Substituting the given values in above equation, we get –

Heat needed = 2 Kg x 390 J/kgºC x 10ºC

= 7800 J

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In reaching her destination, a backpacker walks with an average velocity of 1.41 m/s, due west. This average velocity results, b

V125BC [204]

The total average velocity $v=+1.41 m/s$ (I assume west as positive direction) is given by the total displacement, S, divided by the total time taken, t:
$v= \frac{S}{t}= \frac{S_1+S_2}{t_1+t_2}$
where:
-The total displacement S is the algebraic sum of the displacement in the first part of the motion ( $S_1=6.30 km=6300 m$ , due west) and of the displacement in the second part of the motion ( $S_2$ , due east).
-The total time taken t is the time taken for the first part of the motion, $t_1$ , and the time taken for the second part of the motion, $t_2$ . $t_1$ can be found by using the average velocity and the displacement of the first part:
$t_1= \frac{S_1}{v_1}= \frac{6300 m}{2.49 m/s}=2530 s$

$t_2$ , instead, can be written as $\frac{S_2}{v_2}$ , where $v_2=-0.630 m/s$ is the average velocity of the second part of the motion (with a negative sign, since it is due east).

Therefore, we can rewrite the initial equation as:
$v=1.41 = \frac{6300+S_2}{2530- \frac{S_2}{0.630} }$
And by solving it, we find the displacement in the second part of the motion (i.e. how far did the backpacker move east):
$S_2=-844 m=-0.844 km$

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2 years ago

Quaternary structure is achieved when a protein folds into a compact, three-dimensional shape stabilized by interactions between

Sever21 [200]

Answer:

False: Quaternary structure is achieved when multiple polypeptide chains in protein come together.

Explanation:

There are four levels of protein structure: primary, secondary, tertiary, and Quaternary structure.

Tertiary structure is a protein structure, which is achieved when a protein folds into a compact, three-dimensional shape stabilized by interactions between side-chain R groups of amino acids.

However, Quaternary structure is achieved when multiple polypeptide chains in protein come together.

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3 years ago

In nineteenth century, physical science was divided into discipline. .

dem82 [27]

Answer:

Here! Try this Website!: www.britannica.com › science › physical-science physical science | Definition, History, & Topics | Britannica. So you will learn a lot more about science, history, and topics about it!

8 0

1 year ago

Read 2 more answers

The maximum tension the wire can withstand without breaking is 300 N . A 0.800 kg projectile traveling horizontally hits and emb

topjm [15]

Answer:

Let's investigate the case where the cable breaks.

Conservation of angular momentum can be used to find the speed.

$\vec{L}_1 = \vec{L}_2\\\vec{L}_1 = m\vec{v_0} \\\vec{L}_2 = I\vec{\omega}\\$

The projectile embeds itself to the ball, so they can be treated as a combined object. <u>The moment of inertia of the combined object is equal to the sum of the moment of inertia of both objects. </u>

$I = I_{projectile} + I_{ball}\\I = mr^2 + mr^2\\I = 2mr^2$

where r is the length of the cable.

<u>After the collision, the ball and the projectile makes a circular motion because of the cable.</u> So, the force (tension) in circular motion is

$F = \frac{mv^2}{r}$

The relation between linear velocity and the angular velocity is

$v = \omega r$

So,

$F = \frac{m(\omega r)^2}{r} = m\omega^2 r = 300\\mv_0r =I\omega\\\\\omega = mv_0r/I\\300 = m(\frac{mv_0r}{I})^2r = m(\frac{mv_0r}{2mr^2})^2r = m(\frac{v_0}{2r})^2r = \frac{mv_0^2r}{4r^2} = \frac{mv_0^2}{4r}\\300 = \frac{0.8v_0^2}{4r}\\1500 = v_0^2/r\\v_0 = \sqrt{1500r}$

As can be seen, the maximum velocity for the projectile without breaking the cable is $\sqrt{1500r}$ , where r is the length of the cable.

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3 years ago

As a consultant to the soft-drink industry, Dr. J is given the task of conducting the ultimate Pepsi taste test. This is Dr. J's

dem82 [27]

Answer:

A) How much work does the Pepsi do on the bullet = 0.0625J

B) At what velocity does the Pepsi hit the floor = 7.67m/s

Explanation:

Given mass of bullet = 5g

initial velocity = 500 m/sec

final velocity = 5 m/sec

From work done = Force X Distance

WD = Mad

a = v - u /t

Workdone ; m(v - u )/t

A) The work done by the Pepsi is equal to the change in kinetic energy while in the Pepsi:

but The work done by the container wall on the bullet is equal to the change in kinetic energy on either side of the wall: W = change in kinetic energy = 1/2 mv²

= 1/2 X 0.005 x 500² - 1/2 X 0.055 x 5²

= 624.94J

Therefore ; The work done by the Pepsi is equal to the change in kinetic energy while in the Pepsi = W = change in KE = 0.0625 - 0 = 0.0625J

B) At what velocity does the Pepsi hit the floor?

From conservation of energy principle; PE = KE

mgh = 1/2mv²

0.98 X 3 = 1/2v²

velocity = 7.67m/s

3 0

2 years ago