Answer:
49 N
Explanation:
In order to move the box at constant speed, the acceleration of the box must be zero (a=0): this means, according to Newton's second law,
F = ma
that the net force acting on the box, F, must be zero as well.
Here there are two forces acting on the box in the horizontal direction while it is moving:
- The force of push applied by the guy, F
- The frictional force, 
For an object moving on a flat surface, the frictional force is given by
where
is the coefficient of friction
m is the mass of the box
g is the acceleration of gravity
So the equation of the forces becomes
And substituting:
We find the force that must be applied by the guy:
It's gravitational potential energy at the top will roughly equal it's kinetic energy when it was released (a little is lost to air resistance). Note this will assume the release point is zero potential energy. (we are free to define it that way, just letting you know). Gravitational potential energy is mgh.
mgh=25J
h=25J/(0.5kg x 9.81m/s^2) = 5.097m
So it goes about 5.1 meters above the point where it was released
Answer:
a) the velocity increases then decreases.
Answer:
There is a dependency relationship between the refractive index of each substance and the radiation wavelength.
The refractive index in a given medium is inversely proportional to the wavelength of a color.
For example:
The rays of the red color have a wavelength greater than the rays of the blue color, therefore they have a lower refractive index and consequently a light scattering less than the blue.
Snell's law :
n₂/n₁ = v₁/v₂ = λ₁ /λ₂
*n: (refractive index)
v: (speed of light propagation)
λ: (wavelength)
