How many electron shells does an atom of oxygen have? (A.) 1 (B.) 2 (C.) 3 (D.) 4

Từ ánh sáng từ mặt trời đến nhiệt liên tục phát ra từ cơ thể chúng ta, có nhiều dạng bức xạ khác nhau. Tuy nhiên, khi nói đến bức xạ và nguy cơ ung thư, hầu hết mọi người đều nghĩ đến tia X và tia gamma.

Các nguồn tự nhiên của tia X và tia gamma bao gồm khí radon, chất phóng xạ trong lòng đất và các tia vũ trụ tấn công hành tinh từ không gian. Tuy nhiên, loại bức xạ này cũng có thể do con người gây ra. Tia X và tia gamma được sản xuất trong các nhà máy điện hạt nhân để sử dụng trong các xét nghiệm hình ảnh y tế, điều trị ung thư, chiếu xạ thực phẩm và máy quét an ninh sân bay với liều lượng nhỏ.

English:

From light from the sun to the heat that is continuously emitted from our bodies, there are many different forms of radiation. However, when it comes to radiation and cancer risk, most people think of X-rays and gamma rays.

Natural sources of X-rays and gamma rays include radon gas, underground radioactive material, and cosmic rays that strike the planet from space. However, this type of radiation can also be caused by humans. X-rays and gamma rays are produced in nuclear power plants for use in medical imaging tests, cancer treatments, food irradiation and airport security scanners in small doses.

7 0

3 years ago

Emmy is standing on a moving sidewalk that moves at +2 m/s. Suddenly, she realizes she might miss her flight, so begins to speed

likoan [24]

Answer:

Refer to the attachment for the diagram.

3.53 m/s.

Explanation:

Acceleration is the first derivative of velocity relative to time. In other words, the acceleration is the same as the slope (gradient) of the velocity-time graph. Let $t$ represents the time in seconds and $v$ the speed in meters-per-second.

For $0 < x \le 1$ :

Initial value of $v$ : $\rm 2\;m\cdot s^{-1}$ at $t = 0$ ; Hence the point on the segment: $(0, 2)$ .
Slope of the velocity-time graph is the same as acceleration during that period of time: $\rm 2\; m\cdot s^{-2}$ .
Find the equation of this segment in slope-point form: $v - 2 = 2 (t - 0) \implies v = 2t + 2, \quad 0 < t \le 1$ .

Similarly, for $1 < x \le 2$ :

Initial value of $v$ is the same as the final value of $v$ in the previous equation at $t = 1$ : $t = 2t + 2 = 4$ ; Hence the point on the segment: $(1, 4)$ .
Slope of the velocity-time graph is the same as acceleration during that period of time: $\rm 1\; m\cdot s^{-2}$ .

Find the equation of this segment in slope-point form: $v - 4 = (t - 1) \implies v = t + 3 \quad 1 < t \le 2$ .

For $2 < x \le 3$ :

Initial value of $v$ is the same as the final value of $v$ in the previous equation at $t = 2$ : $t = t + 3 = 5$ ; Hence the point on the segment: $(2, 5)$ .
Slope of the velocity-time graph is the same as acceleration during that period of time: $\rm 0\; m\cdot s^{-2}$ . There's no acceleration. In other words, the velocity is constant.
Find the equation of this segment in slope-point form: $v - 5 = 0 (t - 2) \implies v = 5 \quad 2 < t \le 3$ .

For $3 < x \le 4$ :

Initial value of $v$ is the same as the final value of $v$ in the previous equation at $t = 3$ : $t = 5$ ; Hence the point on the segment: $(3, 5)$ .
Slope of the velocity-time graph is the same as acceleration during that period of time: $\rm -3\; m\cdot s^{-2}$ . In other words, the velocity is decreasing.
Find the equation of this segment in slope-point form: $v - 5 = -3 (t - 3) \implies v = -3t + 14 \quad 3 < t \le 4$ .

For $4 < x \le 5$ :

Initial value of $v$ is the same as the final value of $v$ in the previous equation at $t = 4$ : $t = -3t + 14$ ; Hence the point on the segment: $(4, 2)$ .
Slope of the velocity-time graph is the same as acceleration during that period of time: $\rm 0\; m\cdot s^{-2}$ . In other words, the velocity is once again constant.
Find the equation of this segment in slope-point form: $v - 2 = 0 (t - 4) \implies v = 2\quad 4 < t \le 5$ .

$t = \rm 3.49\;s$ is in the interval $3 < x \le 4$ . Apply the equation for that interval: $v = -3t +14 = \rm 3.53\; m \cdot s^{-1}$ .

4 0

3 years ago

What is the function of the Cytoplasm?

ANEK [815]

It is made up of mostly water and salt. Cytoplasm is present within the cell membrane of all cell types and contains all organelles and cell parts.

The cytoplasm is like a bathtub water because it holds a kind of jelly fluid just like a bathtub

eukaryote is an organism with complex cells, or a single cell with a complex structure.

8 0

3 years ago