Answer:
a. Planets move on elliptical orbits with the Sun at one focus.
Explanation:
Johannes Kepler was an astronomer who discovered that planets had elliptical orbits in the early 1600s (between 1609 and 1619).
The three (3) laws published by Kepler include;
I. The first law of planetary motion by Kepler states that, all the planets move in elliptical orbits around the Sun at a focus.
II. According to Kepler's second law of planetary motion, the speed of a planet is greatest when it is closest to the Sun.
Thus, the nearer (closer) a planet is to the Sun, the stronger would be the gravitational pull of the sun on the planet and consequently, the faster is the speed of the planet in terms motion.
III. The square of any planetary body's orbital period (P) is directly proportional to the cube of its orbit's semi-major axis.
Hence, one of Kepler's laws of planetary motion states that planets move on elliptical orbits with the Sun at one focus. This is his first law of planetary motion.
CORRECT ANSWER:
a- Cell-surface receptors bind polar signaling molecules; intracellular receptors bind nonpolar signaling molecules.
STEP-BY-STEP EXPLANATION:
The complete question from book is
According to Figure 9.6, what is a key difference between cell signaling by a cell-surface receptor and cell signaling by an intracellular receptor?
a- Cell-surface receptors bind polar signaling molecules; intracellular receptors bind nonpolar signaling molecules.
b- Signaling molecules that bind to cell-surface receptors lead to cellular responses restricted to the cytoplasm; signaling molecules that bind to intracellular receptors lead to cellular responses restricted to the nucleus.
c- Cell-surface receptors bind to specific signaling molecules; intracellular receptors bind any signaling molecule.
d- Cell-surface receptors typically bind to signaling molecules that are smaller than those bound by intracellular receptors.
e- None of the other answer options is correct.
<h3><u>Given</u><u>:</u><u>-</u></h3>
Acceleration,a = 3 m/s²
Initial velocity,u = 0 m/s
Final velocity,v = 12 m/s
<h3><u>To</u><u> </u><u>be</u><u> </u><u>calculated:-</u><u> </u></h3>
Calculate the time take by a car.
<h3><u>Solution:-</u><u> </u></h3>
According to the first equation of motion:
v = u + at
★ Substituting the values in the above formula,we get:
⇒ 12 = 0 + 3 × t
⇒ 12 = 3t
⇒ 3t = 12
⇒ t = 12/3
⇒ t = 4 sec
Answer:
through nuclear fusion
Explanation:
The burning of the sun is not chemical combustion. It is nuclear fusion. This combustion releases energy which we experience as the heat and light given off by the flame.
