How is a magnetic field generated?

Given the hypothesis that the element zinc prevents cancer, which of the following procedures BEST exemplifies the nature of sci

lidiya [134]

Answer:D

Explanation: i found the answer in an answer key!

4 0

3 years ago

A ball is thrown upward.

valentina_108 [34]

Answer:

It is 10.75

Explanation:

8 0

3 years ago

A force of 40N is applied to a 28 g mass, what is the acceleration? (round to the hundredths place)

Leno4ka [110]

Answer:

1428.6m/s²

Explanation:

Given parameters:

Force applied on the body = 40N

Mass of the body = 28g

1000g = 1kg

28g will therefore be 0.028kg

Unknown:

Acceleration = ?

Solution:

To solve this problem, we use the expression derived from Newton's second law of motion.

Force = mass x acceleration

Insert the parameters and solve;

40 = 0.028 x acceleration

Acceleration = $\frac{40}{0.028}$ = 1428.6m/s²

7 0

3 years ago

Quartz, SiO2, contains 46.7% silicon by mass. What mass of silicon is present in 348 g of quartz? You must show your work.

anastassius [24]

Answer:162.516 gm

Explanation:

Given

Quartz contains 46.7 % silicon by mass

i.e.Silicon is 46.7 % by mass

Total mass of Quartz m=348 gm

46.7% of 348 gm

$=\frac{46.7}{100}\times 348=162.516 gm$

8 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 $t$ .

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

<u>Deriving the half-life formula</u>

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.