A car accelerates from 20 m\s to 30 m\s in 2 seconds. What is the average acceleration of the car?

(a) What is the entropy change of a 14.6 g ice cube that melts completely in a bucket of water whose temperature is just above t

Alex73 [517]

Answer:

a) 17.81 J/K

b) 33.325 J/K

Explanation:

The expression to use here is the following:

ΔS = Q/T

Where:

Q: heat released or absorbed

T: Temperature in K

Now, in order to do this, we need to gather the data. We know that the temperature in part a) is above the freezing temperature of water, which is 0 ° C or 273 K. and the mass of the ice cube is 14.6 g.

a) Using the water heat of fusion (Cause it's melting), we can calculated the heat released using the following expression:

Q = m * Lf

Lf = 333,000 J/kg

Solving for Q first we have:

Q = (14.6 / 1000) * 333,000

Q = 4,861.8 J

Now, the entropy change is:

ΔS = 4,861.8 / 273

ΔS = 17.81 J/K

b) In this part, we follow the same procedure than in part a) but using the water heat of boiling (Lv = 2,256,000 J/kg), the temperature of boiling which is 100 °C (or 373 K) and the mass of 5.51 g (0.00551 kg)

Calculating the heat:

Q = 0.00551 * 2,256,000 = 12,430.56 J

Now the entropy change:

ΔS = 12,430.56 / 373

ΔS = 33.325 J/K

8 0

3 years ago

Our Sun shines bright with a luminosity of 3.828 x 1025 Watt. Her energies

kifflom [539]

Answer:

a) E = 1.58 10²¹ J , b) Oil = 4,236 107 liter , e) T = 54.3 C

Explanation:

a) To calculate the energy that reaches Earth, let us combine that the power emitted by the Sun is distributed uniformly on a spherical surface

I = P / A

A = 4π r²

in this case the radius of the sphere is the distance from the Sun to Earth r = 1.5 10¹¹ m

I = P / A

I = P / 4π r²

let's calculate

I = 3,828 10²⁵/4 pi (1.5 10¹¹)²

I = 1.3539 10²W / m² = 135.4 W / m2

the energy that reaches the disk of the Earth is

E = I A

the area of a disc

A = π r²

E = I π r²

where r is the radius of the Earth 6.37 10⁶ m

E = 135.4 π(6.37 10⁶)

E = 1,726 10¹⁶ W

This is the energy per unit of time that reaches Earth

t = 1 dai (24h / 1day) (3600s / 1h) = 86400 s

E = 1,826 10¹⁶ 86400

E = 1.58 10²¹ J

b) for this part we can use a direct proportions rule

Oil = 1.58 10²¹ (1 / 37.3 10⁶)

Oil = 4,236 10⁷ liter

c) to silence the surface temperature of the Earth we use the Stefan-Bolztman Law

P = σ A e T⁴

T = $\sqrt[4]{P/Ae}$

nos indicate the refect, therefore the amount of absorbencies

P_absorbed = 0.7 P

let's calculate

T = REA (0.7 1.58 1021 / [pi (6.37 106) 2 1)

T = RER (8,676 106)

T = 54.3 C

b) Among the other factors that must be taken into account is the greenhouse effect, due to the absorption of gases from the atmosphere

4 0

3 years ago

Dierdre drew a diagram to compare the three types of mirrors.

Sholpan [36]

<em>Labels that belong in the marked ares X, Y & Z include;</em>

X: Curves outward

Y: Image may be smaller than object

Z: Image is always virtual

<u>Since the rays never meet, the images formed by convex mirrors are always virtual and smaller than the object, and since they are smaller, the images appear to be further than they actually are.</u>

8 0

3 years ago

<img src="https://tex.z-dn.net/?f=explain%20%5C%3A%20%5C%5C%20%20%5C%5C%20how%20%5C%3A%20rainbow%20%5C%3A%20%20form%20%5C%3A%20%

pishuonlain [190]

<h2>Answer:</h2>

<h2>A rainbow is caused by sunlight and atmospheric conditions. Light enters a water droplet, slowing down and bending as it goes from air to denser water. The light reflects off the inside of the droplet, separating into its component wavelengths--or colors. When light exits the droplet, it makes a rainbow.</h2>

7 0

3 years ago

An RC circuit consists of a resistor with resistance 1.0 kΩ, a 120-V battery, and two capacitors, C1 and C2, with capacitances o

Serhud [2]

Answer:

$Q_t= 8.3 * 10^3 C$