Amass of 30.0 grams hangs at rest from the lower end of a long vertical spring. you add different amounts of additional mass δm to the end of the spring and measure the increase in length δl of the spring due to the additional mass. you plot your data in the form δl (vertical axis) versus δm (horizontal axis). plotted this way, your data lies very close to a straight line that has slope 0.0268 m/kg. what is the force constant k of the spring? use g = 9.80 m/s2.

366N/m

Explanation:

According to Hooke's law:

avoiding the minus symbol and substituting the force to the gravitational force, we have:

The spring constant is 366N/m

the independent variable, the one that is intentionally manipulated, is whether or not the car hits the barrier.

the dependent variable, the one that you measure the response in, is the distance that the washers travel.

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.