Answer:
velocity =displacement/time
and speed =distance/time
There's nothing mysterious about it at all. "Frequency" simply means
"often-ness" ... how often or how frequently something happens.
-- The frequency of traditional meals is 3 per day.
-- The frequency of an equinox is 2 per year.
-- The frequency of my sleeping really late is 1 per week.
-- The frequency of my intense desire to sleep late is 30 per month.
etc.
-- The standard unit of frequency in the SI system is "per second".
The special name for that unit is "Hertz". (Hz)
We have the equation of motion 
, where v i the final velocity, u is the initial velocity, a is the acceleration and s is the displacement
Here final velocity, v = 40m/s
Initial velocity, u = 0 m/s
Displacement s = 2 m
Substituting 
So the baseball pitcher accelerates at 400m/
to release a ball at 40 m/s.
<span>At this distance, and with an orbital speed of 24.077 km/s, Mars takes 686.971 Earth days, the equivalent of 1.88 Earth years, to complete a orbit around the Sun. This eccentricity is one of the most pronounced in the Solar System, with only Mercury having a greater one (0.205).
686.971 rounds to 687
HOPE I HELPED!</span>
Answer:
the force of friction = fk = (uk)n = 402(uk)
the net force acting to accelerate bookcase = ma = (41)(0.12) = 4.9 N
the {assumed horizontal} push force = 65 N
so
65 - fk = 4.9
fk = 65 - 4.9 = 60 N
uk = 60/402 = 0.15 <= ANS
