What does the slope of a position-time graph reveal about an object's motion?

The steeper the slope, the larger the velocity. In this case, the object is going faster.

The more shallow the slope, the smaller the velocity. So the object isn't going as fast as compared to steeper slopes.

If the slope is positive, then the object is moving in the positive direction; otherwise, if the slope is negative, then the object is moving in the negative direction.

If the slope is 0, then the object's velocity is 0 and the object is stationary. Horizontal lines always have a slope of zero.

absorption lines are where light has been absorbed by the atom thus you see a dip in the spectrum whereas.

emission spectra have spikes in the spectra due to atoms releasing photons at those wavelengths.

explanation:

this is poiselle's equation from fluid mechanic in physics. mech eng