<span>Ocean water conducts electrical current because it contains electrolytes. Electrolytes are good conductors of electricity, and are naturally present in appropriate amounts in bodies of water. However, pure water (without electrolytes or metals) is not a conductor of electricity. </span>
The answer is D. If you aren't consistent with your drop positions, then your data may be invalid. To be frank: it basically screws over the experiment.
Answer:
25 m/s
Explanation:
First of all, we can find the acceleration the object by using Newton's second law of motion:

where
F = 20.0 N is the net force applied on the object
m = 4.0 kg is the mass of the object
a is its acceleration
Solving for a, we find

Now we know that the motion of the object is a uniformly accelerated motion, so we can find its final velocity by using the following suvat equation:

where
v is the final velocity
u = 0 is the initial velocity
is the acceleration
t = 5 s is the time
By substituting,

From 50km/h to 0km/h in 0.5s we need next acceleration:
First we convert km/h in m/s:
50km/h = 50*1000/3600=13.8888 m/s
a = v/t = 13.88888/0.5 = 27.77777 m/s^2
Now we use Newton's law:
F=m*a
F=1700*27.7777 = 47222N