1) 5.79 s
2) 98.4 ft/s
Explanation:
1)
The motion of the car is a uniformly accelerated motion (it means it travels with constant acceleration), so we can find the time it takes for the car to stop by using the following suvat equation:

where
s is the distance travelled
v is the final velocity
t is the time
a is the acceleration of the car
In this problem we have:
s = 285 ft is the distance travelled
is the acceleration of the car (negative since the car is slowing down)
v = 0 ft/s is the final velocity of the car, since it comes to a stop
Solving for t, we find:

2)
The initial speed of the car can be found by using another suvat equation, namely:

where
v is the final speed
u is the initial speed
a is the acceleration
t is the time
In this problem, we have:
v = 0 is the final speed of the car
is the acceleration of the car (negative since the car is slowing down)
t = 5.79 s is the total time of motion (found in part 1)
Therefore, the initial speed of the car is:

According to the information provided to define an average density, it is necessary to use the concepts related to mass calculation based on gravitational constants and radius, as well as the calculation of the volume of a sphere.
By definition we know that the mass of a body in this case of the earth is given as a function of

Where,
g= gravitational acceleration
G = Universal gravitational constant
r = radius (earth at this case)
All of this values we have,

Replacing at this equation we have that

The Volume of a Sphere is equal to

Therefore using the relation between mass, volume and density we have that

A control is B, standard for comparison. This is used to compare for example plants and using different fertilizers and then have one with no fertilizer. Controls are basically just a base to the entire experiment
I hope this helps you!:)
Answer:
I think it is False.
Explanation:
I think that a body could not be vertical for every time.