The horizontal speed has no effect on the answer.
It doesn't matter whether you flick a marble horizontally from the roof,
fire a high-power rifle horizontally from the roof, drive a school bus straight
off the roof, or drop a bowling ball from the roof with zero horizontal speed.
Their vertical speed is completely determined by gravity, (and it happens to
be the same for all of them).
Handy dandy formula for the distance covered by anything that starts out
with zero speed and accelerates to the end:
Distance = (1/2) (acceleration) x (time)²
If the beginning of the journey is on Earth, then the acceleration is
9.8 m/s² ... the acceleration of gravity on Earth. We'll assume that
the 55-meter rooftop in the question is part of a building on Earth.
55 meters = (1/2) (9.8 m/s²) x (time)²
Divide each side
by 4.9 m/s² : 55 m / 4.9 m/s² = (time)²
(time)² = (55/4.9) sec²
Square-root
each side: time = √(55/4.9 sec²)
= 3.35 sec .
Oxygen has Atomic number 8 so all isotopes have 8 protons and 8 electrons.
So the number of neutrons in Oxygen-18 = 18 - 8 = 10.
Option B is the correct one.
Answer:
The objects outside the reference frame aren't moving. It appears this way since the vehicle you are inside is moving, but unless the objects are people, animals, or other vehicles, the objects aren't moving.
Equatorial currents are primarily westward. This is because the dominant current in the northern hemisphere has a clockwise direction, while the southern hemisphere has a counterclockwise direction. When these two currents meet at the equator, a common westward current exists.
