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 .
Answer:
According to the travellers, Alpha Centauri is <em>c) very slightly less than 4 light-years</em>
<em></em>
Explanation:
For a stationary observer, Alpha Centauri is 4 light-years away but for an observer who is travelling close to the speed of light, Alpha Centauri is <em>very slightly less than 4 light-years. </em>The following expression explains why:
v = d / t
where
- v is the speed of the spaceship
- d is the distance
- t is the time
Therefore,
d = v × t
d = (0.999 c)(4 light-years)
d = 3.996 light-years
This distance is<em> very slightly less than 4 light-years. </em>
Will this one work?...................
Acceleration in m/s^2 = 2/10 = 0.2 m/s^2
The lowest surface temperature in the solar system was recorded on Uranus (-224 degrees Celsius). The temperature of a planet does not only depend on the amount of solar radiation that it receives but also on the amount of heat that it gives off. Because of Uranus' orientation it absorbs little radiation which makes it colder than Neptune although Neptune is further away from the Sun. <span />
