a₀). You know ... -- the object is dropped from 5 meters above the pavement; -- it falls for 0.83 second.
a₁). Without being told, you assume ... -- there is no air anyplace where the marshmallow travels, so it free-falls, with no air resistance; -- the event is happening on Earth, where the acceleration of gravity is 9.81 m/s² .
b). You need to find how much LESS than 5 meters the marshmallow falls in 0.83 second.
c). You can use whatever equations you like. I'm going to use the equation for the distance an object falls in ' T ' seconds, in a place where the acceleration of gravity is ' G '.
d). To see how this all goes together for the solution, keep reading:
The distance that an object falls in ' T ' seconds when it's dropped from rest is
(1/2 G) x (T²) .
On Earth, ' G ' is roughly 9.81 m/s², so in 0.83 seconds, such an object would fall
(9.81 / 2) x (0.83)² = 3.38 meters .
It dropped from 5 meters above the pavement, but it only fell 3.38 meters before something stopped it. So it must have hit something that was
(5.00 - 3.38) = 1.62 meters
above the pavement. That's where the head of the unsuspecting person was as he innocently walked by and got clobbered.
Alpha decay is one of the three major types of decays, others being, beta decay and gamma decay.
<em><u>When a radioactive isotope undergoes alpha decay it emits alpha particles. An alpha particle is equivalent to the nucleus of Helium atom.</u></em>
<em><u>Therefore, an atom undergoing decay, its atomic mass is decreased by 4 and its atomic number is decreased by 2. </u></em>
Thus, since 232/90 Th, has undergone alpha decay its mass number is reduced by 4 to 228 and its atomic number by 2 to 88, and becomes 228/88 Ra.
