Helium, Neon, and Xenon are all part of the same column on the Periodic Table. Such a column is referred to as a Group, because they have the same number of valence electrons in their outermost shell. Hope this helps!
a). for velocity, you must have a number, a unit, and a direction.
Yes. This one isn't bad. The 'number' and the 'unit' are the speed.
b). the si units for velocity are miles per hour.
No. That's silly.
'miles' is not an SI unit, and 'miles per hour'
is only a speed, not a velocity.
c). the symbol for velocity is .
You can use any symbol you want for velocity, as long as
you make its meaning very clear, so that everybody knows
what symbol you're using for velocity.
But this choice-c is still wrong, because either it's incomplete,
or else it's using 'space' for velocity, which is a very poor symbol.
d). to calculate velocity, divide the displacement by time.
Yes, that's OK, but you have to remember that the displacement
has a direction, and so does the velocity.
Lift force exerted by the air on the rotors=143244 N
Explanation:
we use Newtons second law
F- (M+m)g=(M+m)a
F= lift force
m= mass of helicopter= 13000 Kg
M= mass of car= 2000 lb=907.2 kg
a= acceleration= 0.5 m/s²
g= acceleration due to gravity
F- (M+m)g=(M+m)a
F=(M+m)(a+g)
F=(13000+907.2)(0.5+9.8)
F=143244 N
