Explain 8. How do you know that
the bicyclists in the first
panel above are moving
at a constant velocity?

Constant velocity means that the object in motion is moving in a straight line at a constant speed. You know this as in the first panel each arrow representing each second is the same width apart, therefore you know the cyclists are moving at a constant velocity. Compare this to the second box representing changing speed. The arrows are different lengths meaning each second the cyclists are moving at a different speed and are not moving at a constant velocity.

Hope this helped.

  the unit of the measure =

explanation:

  the property that is quantified by the energy needed per of material to raise the temperature by one.

  si unit of energy = joule (j)

  si unit of temperature = kelvin (k)

  si unit of mass of material = kilogram (kg)

the property that is quantified by the energy needed per of material to raise the temperature by one is called specific heat.

the unit of specific heat is

there are no contact forces mentioned on the list of choices that you've provided.