Answer:
Explanation:
For this problem, we just need to remember conservation of momentum, as there are no external forces in the horizontal direction:

where the suffix i means initial, and the suffix f means final.
The initial momentum will be:

as the second puck is initially at rest:

Using the unit vector
pointing in the original line of motion:



So:


Knowing the magnitude and directions relative to the x axis, we can find Cartesian representation of the vectors using the formula

So, our velocity vectors will be:


We got


So, we got the equations:

and
.
From the last one, we get:




and, for the first one:






so:

and


Question:
The water molecules now in your body were once part of a molecular cloud. Only about onemillionth of the mass of a molecular cloud is in the form of water molecules, and the mass density of such a cloud is roughly 2.0×10−21 g/cm^3.
Estimate the volume of a piece of molecular cloud that has the same amount of water as your body.
Answer:
The volume of cloud that has the same density as the amount of water in our body is 1.4×10²⁵ cm³
Explanation:
Here, we have mass density of cloud = 2.0×10⁻²¹ g/cm^3
Density = Mass/Volume
Volume = Mass/Density = If the mass is 40 kg and the body is made up of 70% by mass of water, we have
28 kg water = 28000 g
Therefore the Volume = 28 kg/ 2.0×10⁻²¹ g/cm^3 = 1.4×10¹⁹ m³ = 1.4×10²⁵ cm³.
Therefore, the volume of cloud that has the same density as the amount of water in our body = 1.4×10²⁵ cm³.
Answer:
b) -10 m/s
Explanation:
In perfectly elastic head on collisions of identical masses, the velocities are exchanged with one another.