Answer:
Explanation:
Since the block is at rest in an elevated position, we can assume that it only has potential energy.
U=mgh is the formula for potential energy where U=potential energy, m= mass, g=acceleration due to gravity, and h=height.
Plug in known variables....
U=4kg*9.8m/s^2*20m
U=784 joules of potential energy or letter A.
<h2>
The rank is : 
.</h2>
We need to rank the objects according to the magnitude of their momentum.
We know momentum ,
{ here m is mass and v is velocity }
Momentum of object A , 
Momentum of object B , 
Momentum of object C , 
Now, we can rank them in order of their magnitude of momentum .
.
Hence, this is the required solution.
Learn More :
Momentum
brainly.com/question/7957458
Answer:
Explanation:
<u>Instant Velocity and Acceleration
</u>
Give the position of an object as a function of time y(x), the instant velocity can be obtained by

Where y'(x) is the first derivative of y respect to time x. The instant acceleration is given by

We are given the function for y

Note we have changed the last term to be quadratic, so the question has more sense.
The velocity is

And the acceleration is
