Calculate the amount of heat needed to convert 0.8 kg of ice at -19 °C into water at 29 °C.

The watermark can be of different types depending on the application. A watermark will resist manipulations of the media. Howeve

Marina86 [1]

<em>The first blank is </em><em>robust watermark</em>; a robust watermark will not resist tampering.

<em>The second blank is </em><em>fragile watermark</em><em>;</em> a fragile watermark will resist manipulations of the media.

<h3>What is a watermark?</h3>

A watermark is a faint design made in paper during manufacture that is visible when held against the light and clearly identifies the maker.

The watermark can be of different types depending on the application and they include:

A robust watermark will not resist tampering.
A fragile watermark will resist manipulations of the media.

Thus, The first blank is robust watermark; a robust watermark will not resist tampering.

The second blank is fragile watermark; a fragile watermark will resist manipulations of the media.

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7 0

2 years ago

A student pulls a block over a rough surface with a constant force FP that is at an angle θ above the horizontal, as shown above

gizmo_the_mogwai [7]

Answer:

B.The force of friction between the block and surface will decrease.

Explanation:

The force of friction is given by

$F_s = \mu N$

where $\mu$ is the coefficient of friction and $N$ is the normal force.

When the student pulls on the block with force $F_p$ at an angle $\theta$ , the normal force on the block becomes

$N = Mg- F_psin(\theta)$

and hence the frictional force becomes

$F_s = \mu (Mg- F_psin(\theta))$ .

Now, as we increase $\theta$ , $sin(\theta)$ increases which as a result decreases the normal force $Mg- F_psin(\theta)$ , which also means the frictional force decreases; Hence choice B stands true.

<em>P.S: Choice D is tempting but incorrect since the weight </em> $W=mg$ <em> is independent of the external forces on the block. </em>

6 0

3 years ago

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What is one characteristic of a sample of matter that indicates it is a pure substance? A) It can be separated using by a physic

snow_lady [41]

D) If the composition of a sample is fixed, the sample is a pure substance.

Explanation:

A) It can be separated by using physical means, such as filtering.

Of course using physical means as filtration or crystallization we increase the purity of a compound, however sometimes impurities may remain dissolved in the solution or they may co-precipitate with the analysed sample.

B) The components in a pure substance do not have to be in definite ratios.

If the components in a substance do not have definite rations it means the the substance is not pure, it is a mixture of something.

C) If the composition of a sample varies, the sample is a pure substance.

If the composition of a sample varies, it means that different components in the substance are changing so it is a clue that the substance is not pure.

D) If the composition of a sample is fixed, the sample is a pure substance.

If the composition of a sample is fixed, and it can be determined and proven, the substance is pure.

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pure substances

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8 0

3 years ago

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Select the correct answer.<br> Which type of energy is thermal energy a form of

elena-s [515]

Kinetic energy. thermal energy (a low form of energy ) is a form of kinetic energy as it is produced as a result of motion of particles either if they vibrate at their position or they move along longer paths. Motion produces friction or resistance which leads to excitation and thus the heat is produced. The higher the motion of the particles, the higher would be the thermal energy.

7 0

3 years ago

A 4.4 nC charge exerts a repulsive force of 36 mN on a second charge which is located

zhenek [66]

The magnitude and sign of the second charge will be + 8.6241×10⁻¹⁹ C. The principal of the Columb's law is used in the given problem.

<h3>What is Columb's law?</h3>

The force of attraction between two charges, according to Coulomb's law, is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.

Charges that are similar repel each other, whereas charges that are diametrically opposed attract each other.

They will repel, moving in opposite directions at the same speed. Because the magnitude and nature of the charge are the same.

The given data in the problem is;

q₁ is the charge 1 = 4.4 nC = 4.4 ×10⁻⁹ C

F is the repulsive force = 36 mN =36 ×10⁶ N

d is the distance = 0.70 m

The Coulomb force is found as;

$\rm F = \frac{Kq_1q_2}{r^2}\\\\\ \rm 36\times 10^6 = \frac{9 \times 10^9 }{(0.7)^2} \times 4.4 \times 10^{-9} \times q_2\\\\\ q_2 = 8.6241 \times 10^{-19 } \ C$

Hence, the magnitude and sign of the second charge will be + 8.6241×10⁻¹⁹ C.

To learn more about Coulomb's law, refer to the link;

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6 0

2 years ago