Can someone tell me how to solve these question below.
16. a man stands on top of a 25 m tall cliff. the man throws a rock upwards at a 25 degree angle above the horizontal with an initial velocity of 7.2 m/s. what will be the vertical position of the rock at t = 2 seconds? what will be the horizontal position of the rock at that time?

Vertical position of the rock after 2 seconds = 11.46 m

Horizontal position of the rock after 2 seconds = 13.06 m

Explanation:

Initial height = 25 m

Angle of throw = 25 degrees

Velocity of throw = 7.2 m/s

Horizontal velocity of throw = 7.2 cos 25 = 6.53 m/s

Vertical velocity of throw = 7.2 sin 25 = 3.04 m/s

Acceleration in horizontal direction = 0 m/s²

Acceleration in vertical direction = -9.8 m/s²

Vertical position of the rock at t = 2 seconds

We have equation of motion s = ut + 0.5at²

                                     s = 3.04 x 2 - 0.5 x 9.81 x 2²

                                     s = -13.54 m

Vertical position = 25 - 13.54 = 11.46 m

Horizontal position of the rock at t = 2 seconds

We have equation of motion s = ut + 0.5at²

                                     s = 6.53 x 2 + 0.5 x 0 x 2²

                                     s = 13.06 m

Horizontal position = 13.06 m

Vertical position of the rock after 2 seconds = 11.46 m

Horizontal position of the rock after 2 seconds = 13.06 m

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explanation:

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.