That particular group of elements is reffered to as the "Noble Gasses"--a title that comes from the fact that these gases are very "secure" and don't mix well with other elements.
Wildlife researcher starts from a and then reaches b, he turns towards north 40 degree to move towards c.
Total displacement is ac
Total horizontal displacement = 4+4 cos40 =7.06 km
Total vertical displacement = 4 sin40 =2.57 km
Total displacement
= 7.51 km
Answer;
=32.15 meters
Explanation;
Use the formula
s= ut+ 0.5 a (t)^2 to find out 's'
where s= distance traveled
u=initial velocity which is zero in this case
t= time taken to travel 's' distance
a=acceleration (due to gravity on moon i.e 1.62 m/s^2 )
Therefore;
S = 0.5 * 1.62 * 6.3 * 6.3
= 32.1489 meters
Thus; the crater is 32.15 meters deep.
Answer:

Explanation:
We must use conservation of linear momentum before and after the collision, 
Before the collision we have:

where these are the masses are initial velocities of both players.
After the collision we have:

since they clong together, acting as one body.
This means we have:

Or:

Which for our values is:
