Asolid ball is at the top of a 2 m tall ramp. if it is given a push so that it’s initial speed is 1.75 m/s, what is it’s speed when it reaches the bottom of the ramp?

6.50m/s

Explanation:

Using conservation of energy, the total energy in the system is conserved. We know that the ball has potential energy initially because it is elevated 2 meters. We also know it has kinetic energy because it is given an initial speed of 1.75 m/s. At the bottom of the ramp, it loses all potential energy and is converted directly to kinetic energy. We can model the equation as below. U is the potential energy, K is the initial kinetic energy and K' is final kinetic energy.

Equation for kinetic energy is

and potential energy is:

Plug these equation to the first equation and simplify (v' is final speed):

Plug in the values:

Final speed is 6.50m/s

the answer is to check all of them! they all apply well at least i think so!

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.