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3 years ago

What type of physical change can always be reversed by heating or cooling?

2 answers:

7 0

The type of physical change that can always be reversed by heating or cooling is : Melting

Melting is a process of transforming solid substance into liquid , usually done by heating. The thing is , this process usually can be reverse by cooling the liquid result back into solid form

hope this helps

Grace [21]3 years ago

6 0

Explanation:

Changes that do not lead to any change in chemical composition of a substance is known as a physical change.

For example, melting point, boiling point, density, volume are known as physical changes.

Melting is a property in which a substance changes from solid state to liquid state.

For example, melting of ice is a physical change which can be reversed by cooling the substance again.

Therefore, we can conclude that melting is a physical change that can always be reversed by heating or cooling.

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A substance that accelerates the rate of a chemical reaction is called a(an)

Dahasolnce [82]

<span>A substance that accelerates the rate of chemical reaction is called a catalyst. It serves as an alternative pathway for the reaction product. The increase of rate of chemical reaction is because catalyst has low activiation energy than the original pathway. The low activation energy will increase the amount of molecules that can benefit in the energy created by the catalyst.</span>

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3 years ago

1. A step-up transformer increases 15.7V to 110V. What is the current in the secondary as compared to the primary? Assume 100 pe

Serjik [45]

1. $I_2 = 0.14 I_1$

Explanation:

We have:

$V_1 = 15.7 V$ voltage in the primary coil

$V_2 = 110 V$ voltage in the secondary coil

The efficiency of the transformer is 100%: this means that the power in the primary coil and in the secondary coil are equal

$P_1 = P_2\\V_1 I_1 = V_2 I_2$

where I1 and I2 are the currents in the two coils. Re-arranging the equation, we find

$\frac{I_2}{I_1}=\frac{V_1}{V_2}=\frac{15.7 V}{110 V}=0.14$

which means that the current in the secondary coil is 14% of the value of the current in the primary coil.

2. 5.7 V

We can solve the problem by using the transformer equation:

$\frac{N_p}{N_s}=\frac{V_p}{V_s}$

where:

Np = 400 is the number of turns in the primary coil

Ns = 19 is the number of turns in the secondary coil

Vp = 120 V is the voltage in the primary coil

Vs = ? is the voltage in the secondary coil

Re-arranging the formula and substituting the numbers, we find:

$V_s = V_p \frac{N_s}{N_p}=(120 V)\frac{19}{400}=5.7 V$

5 0

3 years ago

Define average velocity.Immersive Reader

vagabundo [1.1K]

Answer:

The slope of a graph of position vs time

4 0

3 years ago

A vector has an x-component of length 10 and a y-component of length 3. What is the angle of the vector? (Hint: Use the inverse

Sonja [21]

The vector, the x-component and the y-component form a rectangle triangle where the vector is the hypothenuse and the x and y components are the two sides.
Calling $\alpha$ the angle between the vector and the horizontal direction (x), the two sides are related to $\alpha$ by
$\tan \alpha = \frac{v_y}{v_x}$
where vy and vx are the two components on the y- and x-axis. Using vx=10 and vy=3 we find
$\tan \alpha = \frac{3}{10} =0.3$
And so the angle is
$\alpha = \arctan (0.3)=16.7^{\circ}$

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3 years ago

In a lab, the mass of object A is 2.5 kg. Object A weighs:

dangina [55]

Answer:

25N

Explanation:

Assuming the lab is on earth:

w = mg = 2.5 (9.81) = 25N

8 0

3 years ago