The symbol used for magnetic field is:

Out of the given options, ‘it is described as a fundamental force and therefore does not depend on other forces’ is the true statement about gravity.

Answer: Option B

Explanation:

As we all know that there are four fundamental forces existing in the universe- Electromagnetic force, strong forces, weak forces and the gravitational force.

These are the forces that don’t depend on any other physical force to draw a considerable impact on the physical objects. The gravitational force can be defined as,

$F=G \times \frac{m_{1} m_{2}}{r^{2}}$

Where,

G = Gravitational Constant

$m_{1} , m_{2}$ = Masses of two substances under consideration

R = distance between the two substances.

Looking upon the formula of gravitational force we can easily estimate that the gravitational force relies on the mass of substances and the relative distance between them. There is no factor than the air friction that hinders the gravitational force and that too in a negligible amount.

5 0

3 years ago

The half-life of Iodine-131 is 8.0252 days. If 14.2 grams of I-131 is released in Japan and takes 31.8 days to travel across the

MakcuM [25]

Answer:

Explanation:

Half-life problems are modeled as exponential equations. The half-life formula is $P=P_o\left (\dfrac{1}{2} \right)^{\frac{t}{k}}$ where $P_o$ is the initial amount, $k$ is the length of the half-life, $t$ is the amount of time that has elapsed since the initial measurement was taken, and $P$ is the amount that remains at time $t$ .

$P=14.2\left (\dfrac{1}{2} \right)^{\frac{t}{8.0252}}$

Deriving the half-life formula

If one forgets the half-life formula, one can derive an equivalent equation by recalling the basic an exponential equation, $y=a b^{t}$ , where $t$ is still the amount of time, and $y$ is the amount remaining at time $t$ . The constants a and b can be solved for as follows:

Knowing that amount initially is 14.2g, we let this be time zero:

$y=a b^{t}$

$(14.2)=ab^{(0)}$

$14.2=a *1$

$14.2=a$

So, $a=14.2$ , which represents out initial amount of the substance, and our equation becomes: $y=14.2 b^{t}$

Knowing that the "half-life" is 8.0252 days (note that the unit here is "days", so times for all future uses of this equation must be in "days"), we know that the amount remaining after that time will be one-half of what we started with:

$\left(\frac{1}{2} *14.2 \right)=14.2 b^{(8.0252)}$

$\dfrac{7.1}{14.2}=\dfrac{14.2 b^{8.0252}}{14.2}$

$0.5=b^{8.0252}$

$\sqrt[8.0252]{\frac{1}{2}}=\sqrt[8.0252]{b^{8.0252}}$

$\sqrt[8.0252]{\frac{1}{2}}=b$

Recalling exponent properties, one could find that $\left ( \frac{1}{2} \right )^{\frac{1}{8.0252}}=b$ , which will give the equation identical to the half-life formula. However, recalling this trivia about exponent properties is not necessary to solve this problem. One can just evaluate the radical in a calculator:

$b=0.9172535661...$

Using this decimal approximation has advantages (don't have to remember the half-life formula & don't have to remember as many exponent properties), but one minor disadvantage (need to keep more decimal places to reduce rounding error).

So, our general equation derived from the basic exponential function is:

$y=14.2* (0.9172535661)^t$ or $y=14.2*(0.5)^{\frac{t}{8.0252}}$ where y represents the amount remaining at time t.

Solving for the amount remaining

With the equation set up, substitute the amount of time it takes to cross the Pacific to solve for the amount remaining:

$y=14.2* (0.9172535661)^{(31.8)}$ $y=14.2*(0.5)^{\frac{(31.8)}{8.0252}}$

$y=14.2* 0.0641450581$ $y=14.2*(0.5)^{3.962518068}$

$y=0.9108598257$ $y=14.2* 0.0641450581$

$y=0.9108598257$

Since both the initial amount of Iodine, and the amount of time were given to 3 significant figures, the amount remaining after 31.8days is 0.911g.

8 0

1 year ago

Consider the reaction, X + 2Y → XY2 If X and Y are completely consumed in the reaction and we start with 10.0 mol of Y, then how

Harrizon [31]

Answer:

In the reaction you would have 15.0 mols of Y and X.

Explanation:

The stoichiometric coefficents for X and Y are 1 and 2 respectively, if you start the reaction with 10.0 moles of Y you would need 5.0 moles of X in order to achieve a complete reaction so you will have 15.0 total moles in the reaction, assuming no mass loss and no nuclear reactions.

3 0

3 years ago

A tow truck pulls a 7,800 N car 5m out of a ditch in 6.5 seconds. How much power does the

rosijanka [135]

Answer:

p=6000W

Explanation:

p=w/t

w=f*d=7800*5=39000 J

therefore,

p=39000/6.5=6000 W

6 0

3 years ago

Which statement best describes perigee?

Alex17521 [72]

Whenever you see "-gee" in the description of a point in an orbit,
you know it's talking about an orbit of the Earth. You see the same
piece of a word in "geology" and "geography". "Geometry" began
as the study of measuring places on the Earth, so that you and your
neighbor could agree on where your field ends and his begins, and
if you wanted to buy part of his field from him, the two of you could
go outside, do some measurements, and agree on what area you're
paying him for.

"Perigee" and "apogee" are the points in the orbit of the Moon, or a
TV satellite, or the International Space Station, where the orbiting body
is nearest or farthest from the Earth. "Perigee" is the lowest/nearest point.
"Apogee" is the highest/farthest point.

If the description has "-helion" in it instead of "-gee", then it's talking about
an orbit around the sun, like points in the Earth's orbit. The "-helion" comes
from the Greek word "Helios" for the Sun.
Earth is at perihelion during the first few days of January, and at aphelion
during the first few days of July. (That's right ... nearest to the sun in January,
and farthest from the sun in July.)

6 0

3 years ago