The dirt pushing back is the 'resistance' force. It RESISTS your attempts to shovel it.
The correct answer is answer choice B.
In order to read the publications of his peers, or read his own notes of the work
that he did on the previous day, or find his coffee mug on his desk in the lab, the
research scientist must arrange to have each of them illuminated with visible
wavelengths of light, and then he must catch the light reflected from each of them
with his eyes.
c. -98 m/s
The motion of the rock is a uniformly accelerated motion (free fall) with constant acceleration 
(negative since it is downward). Therefore, we can find its velocity using the following suvat equation
where
v is the final velocity
u is the initial velocity
g is the acceleration of gravity
t is the time
For the rock in the problem,
u = 0
So, its velocity at t = 10 s is
where the negative sign indicates that the velocity points downward.
d. -490 m
Since the motion is at constant acceleration, we can use another suvat equation:
where
s is the displacement
u is the initial velocity
g is the acceleration of gravity
t is the time
Substituting:
u = 0
t = 10 s
We find the rock's displacement:
where the negative sign means the displacement is downward.
Answer:
Hey there!
Mixtures are physically combined and can be separated. For example, sand and water is a mixture.
Pure substances are samples of matter with definite, and unchangeable chemical properties. For example, diamond is a pure substance.
Let me know if this helps :)
