For this case we have that by definition, the kinetic energy is given by the following formula:

Where:
m: It is the mass
v: It is the velocity
According to the data we have to:

Substituting the values we have:

finally, the kinetic energy is 
Answer:
Option A
Answer:
The magnitude of the resultant decreases from A+B to A-B
Explanation:
The magnitude of the resultant of two vectors is given by

where
A is the magnitude of the first vector
B is the magnitude of the second vector
is the angle between the directions of the two vectors
In the formula, A and B are constant, so the behaviour depends only on the function
. The value of
are:
- 1 (maximum) when the angle is 0, so the magnitude of the resultant in this case is

- then it decreases, until it becomes 0 when the angle is 90 degrees, where the magnitude of the resultant is

- then it becomes negative, and continues to decrease, until it reaches a value of -1 when the angle is 180 degrees, and the magnitude of the resultant is

The train would need the greatest amount of force due to weight! If you think of it, a baseball won't need much force to stop it, but if you have a heavy train, it will need excessive force to stop the train. The answer would be #3
I hope this answer helps!
Sorry if it doesn't make sense, as I don't know that much about physics! I am just thinking of what makes sense.
50m
Explanation:
Displacement is the length of path traveled which is measured from start to the finishing of the path.
Analysis of the journey;
Starts from:
0 30m from right
15m to left
50m to right
The displacement is 50m from the starting point.
Distance is total path traveled and for this problem it is 30+ 15 + 50 = 95m
learn more:
displacement brainly.com/question/5461768
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