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4 years ago

6

A plastic-foam container used as a picnic cooler contains a block of ice at 0°C. If 225g of ice melts, how much heat passes thro

ugh the walls of the container?

1 answer:

Dima020 [189]4 years ago

8 0

Answer:

18kcal

Explanation:

Melting enthalpy of water: 80 cal/g

The melting enthalpy discribes how much heat is needed to melt a substance. So you get the heat by multiplying the mass of your substance with its melting enthalpy.

225g*18cal/g=18000cal=18kcal

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A majorette in a parade is performing some acrobatic twirlings of her baton. Assume that the baton is a uniform rod of mass 0.12

den301095 [7]

Question

Initially, the baton is spinning about a line through its center at angular velocity 3.00 rad/s. What is its angular momentum? Express your answer in kilogram meters squared per second.

Answer:

$0.0192 kgm^{2}/s$

Explanation:

The angular momentum L of the baton moving about an axis perpendicular to it, passing through the center of the baton is,

$L = \frac{1}{{12}}m{l^2}\omega$

Here, l is the length of the baton.

Substitute 0.120 kg for m, 3 rads/s for $\omega[\tex] and 0.8 m for l [tex]\begin{array}{c}\\L = \frac{1}{{12}}m{l^2}\omega \\\\ = \frac{1}{{12}}\left( {0.120{\rm{ kg}}} \right){\left( {{\rm{80}}{\rm{.0 cm}}} \right)^2}{\left( {\frac{{1 \times {{10}^{ - 2}}{\rm{m}}}}{{1{\rm{ cm}}}}} \right)^2}\left( {{\rm{3}}{\rm{.00 rad/s}}} \right)\\\\ = 0.0192{\rm{ kg}} \cdot {{\rm{m}}^{\rm{2}}}{\rm{/s}}\\\end{array}$

5 0

4 years ago

Read 2 more answers

A flat loop of wire consisting of a single turn of cross-sectional area 8.20 cm2 is perpendicular to a magnetic field that incre

olga nikolaevna [1]

Answer:

The induced current is $I = 6.25*10^{-4} \ A$

Explanation:

From the question we are told that

The number of turns is $N = 1$

The cross-sectional area is $A = 8.20 cm^2 = 8.20 * 10^{-4} \ m^2$

The initial magnetic field is $B_i = 0.500 \ T$

The magnetic field at time = 1.02 s is $B_t = 2.60 \ T$

The resistance is $R = 2.70\ \Omega$

The induced emf is mathematically represented as

$\epsilon = - N * \frac{ d\phi }{dt}$

The negative sign tells us that the induced emf is moving opposite to the change in magnetic flux

Here $d\phi$ is the change in magnetic flux which is mathematically represented as

$d \phi = dB * A$

Where dB is the change in magnetic field which is mathematically represented as

$dB = B_t - B_i$

substituting values

$dB = 2.60 - 0.500$

$dB = 2.1 \ T$

Thus

$d \phi = 2.1 * 8.20 *10^{-4}$

$d \phi = 1.722*10^{-3} \ weber$

So

$|\epsilon| = 1 * \frac{ 1.722*10^{-3}}{1.02}$

$|\epsilon| = 1.69 *10^{-3} \ V$

The induced current i mathematically represented as

$I = \frac{\epsilon}{ R }$

substituting values

$I = \frac{1.69*10^{-3}}{ 2.70 }$

$I = 6.25*10^{-4} \ A$

7 0

4 years ago

Minions are a happy color yellow. Which of the following statements about minions is correct?

likoan [24]

D all of the above
Hope it helps

6 0

3 years ago

Explain what causes STIs and how they are transmitted

aliya0001 [1]

Hey, Terrizzif!
STIs are caused by sexual transmission, they are spread by sexual intercourse.
I hope this helps;)

7 0

4 years ago

What is the smallest value of n for which the wavelength of a Balmer series line is less than 400 nm

Natasha_Volkova [10]

Answer:

The smallest value is n= 2

Explanation:

The balmer equation is given below

1/λ = R(1/4 - 1/n₂²).

R= 1.0973731568508 × 10^7 m^-1

λ= 400*10^-9 m

(400*10^-9)= 1.0973731568508 × 10^7 (1/4-1/n²)

(400*10^-9)/1.0973731568508 × 10^7

= 1/4 - 1/n²

364.51 *10^-16= 1/4 - 1/n²

1/n²= 1/4 -364.51 *10^-16

1/n² = 0.25-3.6451*10^-14

1/0.25= n²

4= n²

√4= n

2= n

The smallest value is N= 2

7 0

3 years ago