Answer:
2.92682 m

250000000000 Hz

0.21126 m
0.12244 m
Explanation:
c = Speed of light = 
= Wavelength
f = Frequency
Wavelength is given by

The wavelength is 2.92682 m
Frequency is given by

The frequency is 

The frequency is 250000000000 Hz

The wavelength is 

The wavelength is 0.21126 m

The wavelength is 0.12244 m
Here are the missing questions:
(a) How fast is the skier moving when she gets to the bottom of the hill?
(b) How much internal energy was generated in crossing the rough patch?
Part A
The initial kinetic energy of the skier is:

Part of this energy is then used to do work against the force of friction. Force of friction on the horizontal surface can be calculated using following formula:

The work is simply the force times the length:

So when the skier passes over the rough patch its energy is:

When the skier is going down the skill gravitational potential energy is transformed into the kinetic energy:

So the final energy of the skier is:

This energy is the kinetic energy of the skier:
Part B
We know that skier lost some of its kinetic energy when crossing over the rough patch. This energy is equal to the work done by the skier against the force of friction.
Answer:
393.6m/s
Explanation:
Given parameters:
Acceleration = 8.5m/s²
Distance = 300m
Final velocity = 400m/s
Unknown:
Initial velocity = ?
Solution:
To solve this problem, we use the expression below;
v² = u² + 2as
v is the final velocity
u is the initial velocity
a is the acceleration
s is the distance
So;
v² - 2as = u²
u² = v² - 2as
u² = 400² - (2 x 8.5 x 300)
u = 393.6m/s
Answer:
3600
Explanation:
90 of 120 is 3/4 so 4800 - 1200 is 3600.