Answer:
Explanation:
The best way to do this is to remember the rule about the halfway mark in a parabolic path. At a trajectory's half way point in its travels, it will be at its max height. To get the total time in the air, we take that time at half way and double it. Here's what we know that we are told:
initial velocity is 20 m/s
Here's what we know that we are NOT told:
a = -9.8 m/s/s and
final velocity is 0 at an object's max height in parabolic motion.
We will use the equation:
where v is final velocity and v0 is initial velocity. Filling in:
0 = 20 + (-9.8)t and
-20 = -9.8t so
t = 2 seconds. The stone reaches its max height 2 seconds after it is thrown; that means that after another 2 seconds it will be on the ground. Total air time is 4 seconds.
Answer:

Explanation:
The density of the solid is

we want to convert it into kg/m^3. We must note that:

Therefore, the conversion can be done as follows:

We do not feel the gravitational forces from objects other than the Earth because they are weak.
Answer:
Sphere B has 4 times more inertia than sphere A.
Explanation:
Inertia on a Solid sphere is given by:

For this problem:
ma = mb = M
Rb = 2*Ra
With these values:


As you can see, Ib = 4 * Ia.
He is describing the motorcycle's acceleration. <span />