Answer:

Explanation:
Using the given equation, we calculate the energy associated with the excited state
and 

Helium has an atomic number (Z) equal to 2, for n=8:

For n=4:

When an electron jumps from an energy level with greater energy
to one with lower energy
the wavelength of the emitted photon is given by:

h is the Planck constant and c the speed of light in vaccum. So, we have:

Answer:
Bike
Explanation:
bike is the most complex on here, chain, brakes, gears, and tries,
inclined plank is a little complex, gears and plates
lever requires gears or eletric wires,
and least complex is A screw
Answer:
kinetic friction may be greater than 400 N or smaller than 400 N
Explanation:
As we know that maximum value of static friction on the rough surface is known as limiting friction and the formula of this limiting friction is known as

now when object is sliding on the rough surface then the friction force on that surface is known as kinetic friction and the formula of kinetic friction is known as

now we know that

so here value of limiting static friction force is always more than kinetic friction
also we know that
initially when body is at rest then static friction value will lie from 0 N to maximum limiting friction
and hence kinetic friction may be greater than static friction or if the static friction is maximum limiting friction then kinetic friction is smaller than static friction
so kinetic friction may be greater than 400 N or smaller than 400 N
noting or pertaining to a speed less than that of sound in air at the same height above sea level.
Answer:
3565 J
Explanation:
F = Force applied = 1550 N
s = Displacement caused by the applied force = 2.3 m
= Angle at which the force is applied = 0°
When we multiply force, displacement and the angle at which the force is applied we get work
Work done is given by

The work done by team A is 3565 J