Answer:
The answer to your question is 784.8 J. None of your answer, did you forget some information?
Explanation:
Data
mass = 20 kg
distance = 4 m
work = ?
Formula
Work = force x distance
Force = mass x gravity
Process
1.- Calculate the weight of the block
Weight = 20 x 9.81
Weight = 196.2 N
2.- Calculate the work done
Work = 196.2 x 4
Work = 784.8 J
Using the idea of motion under gravity, it will take 0.5 seconds more before the phone hits the ground.
<h3>What is the distance covered?</h3>
The distance covered is obtained form the equations of kinematics under gravity.
Now;
v = u + gt
Recall that it was dropped from a height hence u = 0 m/s
v = gt
v = 9.8 m/s^2 * 4 s
v = 39.2 m/s
Now;
h = ut + 1/2gt^2
but u = 0 m/s
h = 1/2gt^2
h = 1/2 * 9.8 * (4)^2
h = 78.4 m
The phone will not hit the ground within this time
For the phone to hit the ground;
h = 1/2gt^2
if h = 100 m
100 = 1/2 * 9.8 * t^2
2 * 100/9.8 = t^2
t = √2 * 100/9.8
t = 4.5 seconds
It will take about 0.5 seconds more before the phone will hit the ground.
Learn more about motion under gravity:brainly.com/question/15120445
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<span>when two hydrogen atoms approach each other the potential energy of the combination becomes lower and lower until it reaches a minimum value of -436 kl/mol at a distance of 75 pm</span>
<u>D: Half</u>
We know that,
F = m.a, where F is the force, m is the object's mass and a is the acceleration.
In the first case, we observed that a1 = F/m.
In the second case, we observed that the mass has been doubled, so a2 = F/2m .
By the ratio of the two cases, we get
a1/a2 = F/m / F/2m
or, a1/a2 = 2
or, a1 = 2.a2
or, a1/2 = a2
Therefore, the acceleration gets <u>half</u> of it's original measurement.
It's being planned to launch in the 2020's
