D. They are heterotrophs that digest food internally.
The deceleration experienced by the gymnast is the 9 times of the acceleration due to gravity.
Now from Newton`s first law, the net force on gymnast,

Here, W is the weight of the gymnast and a is the acceleration experienced by the gymnast (
acceleration due to gravity)
Therefore,
OR 
Given
and
Substituting these values in above formula and calculate the force exerted by the gymnast,


The only graph that accurately depict the given motion is graph D.
The given parameters;
- initial position of the man = 0
- direction of the man's first displacement = backward
- time of first motion, t₁ = 6 seconds
- velocity of this first displacement = v₁
- time without any motion (<em>zero movement</em>) = 6 seconds
- direction of the second displacement = forward
- velocity of second displacement = 2v₁
Let the acceleration of the first displacement = a
Acceleration of the second displacement = 2a
From the given graphs we can eliminate every graph without initial decrease or motion towards the negative direction.
The only options with initial motion towards the negative direction are;
The difference between graph B and D;
- in graph B there is a uniform motion for 6 seconds
- in graph D there is no motion for 6 seconds (<em>this is obvious as the line fall directly on top of the horizontal axis maintaining a value of zero for 6 seconds</em>).
Thus, the only graph that accurately depict the given motion is graph D.
Learn more here: brainly.com/question/21095906
B) The amount of work done
Answer:
velocity during second d = 20.0 mi/h
Explanation:
Total distance travelled is 2d, with an average velocity of 30.0 mi/h you can express the time travelled in terms of d:
distance = velocity * time
time = distance / velocity
time = 2d/30.0
The time needed for the first d at 60.0 is:
time = d/60.0
The time in the second d you can get it by substracting both times (total time - time for the first d)
second d time = 2d/30.0 - d/60.0
= 4d/60.0 - d/60.0
= 3d/60.0
and with the time (3d/60.0) and the distance travelled (d) you can get the velocity:
velocity = distance / time
velocity = d / (3d/60.0)
= 60.0/3 = 20.0 mi/h