I think it may be c i learned about this last year
Answer:

Explanation:
<u>Uniform Acceleration
</u>
When an object changes its velocity at the same rate, the acceleration is constant.
The relation between the initial and final speeds is:

Where:
vf = Final speed
vo = Initial speed
a = Constant acceleration
t = Elapsed time
It's known a train moves from rest (vo=0) to a speed of vf=25 m/s in t=30 seconds. It's required to calculate the acceleration.
Solving for a:

Substituting:


After plugging all the data into the equation, the result of the relative centrifugal force (RCF) is measured in terms of g.
<h3>What is relative centrifugal force?</h3>
The relative centrifugal force (RCF) or the g force is the radial force generated by the spinning rotor as expressed relative to the earth's gravitational force.
RCF = ac/g
where;
- ac is centripetal acceleration
- g is acceleration due to gravity

where;
<h3>For example, </h3>
Find the maximum RCF of the JS-4.2 rotor can be obtained from its maximum speed (4200 rpm) and its rmax (250 mm);

Thus, after plugging all the data into the equation, the result is measured in terms of g.
Learn more about relative centrifugal force here: brainly.com/question/26887699
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The correct answer is c because B) is a vector which includes both velocity and direction
Answer:
Explanation:
Let acceleration of fall be a .
v² = u² + 2as
v = 3.8 m /s
u = 0
s = 3.5 m
3.8² = 0 + 2 x a x 3.5
a = 2.06 m /s²
Since this acceleration is less than g , an upward force is acting on the firefighter in the form of friction . Let this force be F . Let mass of the firefighter be m .
m = 765 / 9.8
= 78.06 kg
mg - F = ma
765 - F = 78.06 x 2.06
765 - F = 160.8
F = 604.2 N .