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4 years ago

Melting, boiling, and bending are considered physical changes, but burning is a chemical change. Explain why this is so.

2 answers:

7 0

Burning is a chemical change because the particles undergo a molecular change when they are burned. Here is an example- wood turning to smoke.

SVEN [57.7K]4 years ago

5 0

If you melt, boil, or bend an item, it is still the same thing. For instance, If you melt a sugar cube, it will stay as sugar. But if you burn paper, it will turn into ash. Hope this helps!

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A proton moves through a magnetic field at 20.3 % of the speed of light. At a location where the field has a magnitude of 0.0062

galina1969 [7]

Answer:

Force on the proton will be $.73\times 10^{-14}N$

Explanation:

We have given speed of proton is 20.3% of speed of light

Speed of light $c=3\times 10^8m/sec$

So speed of proton $v=\frac{3\times 10^8\times 23}{100}=6.9\times 10^7m/sec$

Magnetic field B = 0.00629 T

Charge on proton $q=1.6\times 10^{-16}C$

Angle between velocity and magnetic field $\Theta =137^{\circ}$

Force on the proton is equal to $F=qvBsin\Theta =1.6\times 10^{-19}\times 6.9\times 10^7\times 0.00629\times sin(137^{\circ})=4.73\times 10^{-14}N$

4 0

3 years ago

A car is traveling at a speed of 50 km/hr. The positive y-axis is north and the positive x-axis is east. Resolve the car's veloc

hjlf

We need to draw a coordinates. the east and south should be the north vector for horizontal line 50 KM in distance is zero. the south is a negative. the south east and north west we should draw the 45 degrees angle in the approprate quadrant and then use the 1-1-sqrt(2) have a relationship in 45-45-90 triangles to resolve the N/S, E/W components.

hope this help

6 0

3 years ago

The first-order rearrangement of CH3NC is measured to have a rate constant of 3.61 × 10–15 s–1 at 298 K and a rate constant of 8

netineya [11]

Answer:

The activation energy for this reaction, Ea = 159.98 kJ/mol

Explanation:

Using the Arrhenius equation as:

$ln\frac {K_2}{K_1}=-\frac {E_a}{R}\times (\frac {1}{T_2}-\frac {1}{T_1})$

Where, Ea is the activation energy.

R is the gas constant having value 8.314 J/K.mol

K₂ and K₁ are the rate constants

T₂ and T₁ are the temperature values in kelvin.

Given:

K₂ = 8.66×10⁻⁷ s⁻¹ , T₂ = 425 K

K₁ = 3.61×10⁻¹⁵ s⁻¹ , T₁ = 298 K

Applying in the equation as:

$ln\frac {8.66\times 10^{-7}}{3.61\times 10^{-15}}=-\frac {E_a}{8.314}\times (\frac {1}{425}-\frac {1}{298})$

Solving for Ea as:

Ea = 159982.23 J /mol

1 J/mol = 10⁻³ kJ/mol

Ea = 159.98 kJ/mol

7 0

3 years ago

Statie electricity refers to the transfer of _______

Nezavi [6.7K]

Static electricity is the result of an imbalance between negative and positive charges in an object. These charges can build up on the surface of an object until they find a way to be released or discharged. ... The rubbing of certain materials against one another can transfer negative charges, or electrons.

3 0

3 years ago

Which statement correctly describes variable stars?

Kryger [21]

Answer:

Explanation:

The Period-Luminosity relationship tells us that luminosity increases with the period, and of course the more luminosity a star has the more far away they can be seen, so from this we know that:

A) False since lower luminosities can be observed when they are close.

B) False since longer periods means higher luminosities

C) False since lower luminosities can be observed when they are close.

D) True: Variable stars with shorter periods have lower luminosities, so they can only be observed when they are close.

5 0

3 years ago