Answer:
bromine
Explanation:
Any element in the halogen group will have seven valence electrons. These elements include fluorine, chlorine, bromine, iodine, and astatine
What information can scientists obtain from tree rings?
Answer's <u>I chose</u>:
<h3>how narrow the rings are</h3><h3>how the climate changed in the tree’s life</h3><h3>how wide the rings are</h3>
Please <u>correct</u> me if there are <em>more </em>or <em>less</em>
Please give a brainliest and a thanks.
<h2>❣</h2>
Wow ! This is not simple. At first, it looks like there's not enough information, because we don't know the mass of the cars. But I"m pretty sure it turns out that we don't need to know it.
At the top of the first hill, the car's potential energy is
PE = (mass) x (gravity) x (height) .
At the bottom, the car's kinetic energy is
KE = (1/2) (mass) (speed²) .
You said that the car's speed is 70 m/s at the bottom of the hill,
and you also said that 10% of the energy will be lost on the way
down. So now, here comes the big jump. Put a comment under
my answer if you don't see where I got this equation:
KE = 0.9 PE
(1/2) (mass) (70 m/s)² = (0.9) (mass) (gravity) (height)
Divide each side by (mass):
(0.5) (4900 m²/s²) = (0.9) (9.8 m/s²) (height)
(There goes the mass. As long as the whole thing is 90% efficient,
the solution will be the same for any number of cars, loaded with
any number of passengers.)
Divide each side by (0.9):
(0.5/0.9) (4900 m²/s²) = (9.8 m/s²) (height)
Divide each side by (9.8 m/s²):
Height = (5/9)(4900 m²/s²) / (9.8 m/s²)
= (5 x 4900 m²/s²) / (9 x 9.8 m/s²)
= (24,500 / 88.2) (m²/s²) / (m/s²)
= 277-7/9 meters
(about 911 feet)
Newton's first law of motion says something like "An object remains
in constant, uniform motion until acted on by an external force".
Constant uniform motion means no change in speed or direction.
If an object changes from rest to motion, that's definitely a change
of speed. So it doesn't remain in the state of constant uniform
motion (none) that it had when it was at rest, and that tells us
that an external force must have acted on it.
Answer:
0.15625 grams
Explanation:
Half life: It is related to the decay of radioactive material. The duration in which half of the material will be degraded/decayed. That means after half life 50% of the radioactive material will be left. Here the half life is 28 years.
Initial quantity of the sample: 2.5 grams.
After 28 years, the leftover quantity = 1.25 grams
After 56 years, the leftover quantity = 0.625 grams
After 84 Years, the leftover quantity = 0.3125 grams
After 112 years, the leftover quantity = 0.15625 grams