Answer:
B, it includes a control group and an experimental group.
G2V
The sun is a G2v type of star, a yellow dwarf and main sequence star.
Its B polaris seems smaller than the Sun
1). The forces inside the atom are always, totally, completely, electrostatic forces. Those are so awesomely stronger than the gravitational forces that the gravitational ones are totally ignored, and it doesn't change a thing.
Parts 2 and 3 of this question are here to show us how the forces compare.
Part-2). The electrostatic force between a proton and an electron.
The constant in the formula is 9x10^9, and the elementary charge is 1.602 x 10^-19 Coulomb ... same charge on both particles, but opposite signs.
I worked through it 3 times and got 0.000105 N every time. So the best choice is 'C', even though we disagree by a factor of ten times. You'll see in part-3 that it really doesn't make any difference.
Part-3). Gravitational force between a proton and an electron.
The constant in Newton's gravity formula is 6.67x10^-11 . You'll have to look up the masses of the proton and the electron.
I got 2.163 x 10^-55 N ... exactly choice-C. yay !
Now, after we've slaved over a hot calculator all night, the thing that really amazes us is not only that the electrostatic force is stronger than the gravitational force, but HOW MUCH stronger ... 10^51 TIMES stronger. That's a thousand trillion trillion trillion trillion times stronger !
That's why it has no effect on the measurements if we just forget all about the gravitational forces inside the atom.
Answer:
Gravity: downwards
Air drag and air-pressure on the inner surface of the the parachute: Upwards
Explanation:
- If a sky-diver is in the final stages of his descend with open parachute such that the wind is calm and it does not blows him laterally.
- In such a condition the air resistance in the form of drag and the pressure force due to the air captured in the parachute are acting in the upward direction which balance the force of gravity on the body. But this situation may occur momentarily and then again the diver must begin to slowly descend.
