All categories

3 years ago

HELP ME, I WILL RATE 5 STARS AND I WILL HEART ANSWER.

Physics

1 answer:

Sidana [21]3 years ago

8 0

Answer:

im going to guess the 3rd one

Explanation:

You might be interested in

The count rate of a radioactive source decreases from 1600 counts per minute to 400 counts per minute in 12 hours. What is the h

kirill115 [55]

Answer:

$t_{1/2}=6 h$

Explanation:

Let's use the decay equation.

$A=A_{0}e^{-\lambda t}$

Where:

A is the activity at t time
A₀ is the initial activity
λ is the decay constant

We know that $\lambda=\frac{ln(2)}{t_{1/2}}$

So we have:

$\lambda=\frac{ln(A/A_{0})}{t}$

$\frac{ln(2)}{t_{1/2}}=\frac{ln(A/A_{0})}{t}$

$t_{1/2}=\frac{t*ln(2)}{ln(A/A_{0})}$

$t_{1/2}=6 h$

Therefore, the half-life of the source is 6 hours.

I hope it helps you!

4 0

3 years ago

Which states the purpose of an experiment?

Whitepunk [10]

B; to produce a hypothesis.

6 0

3 years ago

Read 2 more answers

From a window 20 feet above the ground, the angle of elevation to the top of a building across the street is 78°, and the angle

Papessa [141]

The answer would be 371.16 ft.

Refer to the diagram for the scenario. The drawing is not to scale.

Notice the diagram that you will find to adjacent right triangles. All you need to do is first solve for the needed side of one triangle, by using one side.

It sounds confusing I know, but let's do this step by step.

Angle of depression is 15°.

We use this first because we do not have enough data to use the angle of elevation.

To get the adjacent side, we use the trigonometric function TOA which means:

$tan\theta= \dfrac{opposite}{adjacent}$

We use the height of the first building as our reference, so our given will be:

Opposite = 20ft

θ = 15°

Now we put that into our formula:

$tan\theta= \dfrac{opposite}{adjacent}$

$Tan15 = \dfrac{20ft}{adjacent}$

$adjacent = \dfrac{20ft}{Tan15}$

Adjacent = 74.64 ft

Angle of elevation is 78°:

Now that we have that we can solve for the height from the point of 20ft. We use the same formula, because we are looking for the opposite, given the adjacent.

$tan\theta= \dfrac{opposite}{adjacent}$

$Tan78 = \dfrac{opposite}{74.64ft}$