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4 years ago

Why is it helpful to study the light that comes off stars?

1 answer:

6 0

It is helpful to study the light that comes off stars because C. The light from a star gives hints of what elements make up a star.

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How does the area of 0.3 m2 of iron change when heated from 20 ° C to 60 ° C?

DerKrebs [107]

Answer:

The quantitative relationship between heat transfer and temperature change contains all three factors: Q = mcΔT, where Q is the symbol for heat transfer, m is the mass of the substance, and ΔT is the change in temperature. The symbol c stands for specific heat and depends on the material and phase. The specific heat is the amount of heat necessary to change the temperature of 1.00 kg of mass by 1.00ºC. The specific heat c is a property of the substance; its SI unit is J/(kg ⋅ K) or J/(kg ⋅ ºC). Recall that the temperature change (ΔT) is the same in units of kelvin and degrees Celsius. If heat transfer is measured in kilocalories, then the unit of specific heat is kcal/(kg ⋅ ºC).

Explanation:

6 0

3 years ago

a circuit has a total resistance of 5 ohms and a current of 0.3 amperes. What voltage must the battery supply?

iren [92.7K]

Answer:

1.5volts

Explanation:

V=IR =0.3×5=1.5volts

5 0

4 years ago

A ball rolls down the hill which has a vertical height of 15 m. Ignoring friction what would be the gravitational potential ener

trasher [3.6K]

a) Potential energy: 147 m [J]

The gravitational potential energy of an object is given by

$U=mgh$

where

m is its mass

$g=9.8 m/s^2$ is the acceleration of gravity

h is the height of the object above the ground

In this problem,

h = 15 m

We call 'm' the mass of the ball, since we don't know it

So, the potential energy of the ball at the top of the hill is

$U=(m)(9.8)(15)=147 m$ (J)

b) Velocity of the ball at the bottom of the hill: 17.1 m/s

According to the law of conservation of energy, in absence of friction all the potential energy of the ball is converted into kinetic energy as the ball reaches the bottom of the hill. Therefore we can write:

$U=K=\frac{1}{2}mv^2$

where

v is the final velocity of the ball

We know from part a) that

U = 147 m

Substituting into the equation above,

$147 m = \frac{1}{2}mv^2$

And re-arranging for v, we find the velocity:

$v=\sqrt{2\cdot 147}=17.1 m/s$

5 0

4 years ago

Isotope what is the meaning

Nesterboy [21]

Isotope means that a chemical element that has the same number of protons but neutron number differs.

<u>Explanation:</u>

In isotope, the chemical element differs in neutron and nucleon number. Thus, different isotopes of a single component hold the same place in the periodic table.

Within the atom’s nucleus, protons are defined as an atomic number that is significantly equal to electrons in a neutral atom. An isotope of a given element has a different mass number. In general, every atomic number has a specific element, but in isotope, an atom may have a wide range of neutrons.

3 0

3 years ago

Force is a vector because it has both ___

scoray [572]

Answer:

C. Size and Direction

6 0

3 years ago