Answer:
The found acceleration in terms of h and t is:

Explanation:
(The complete question is given in the attached picture. We need to find the acceleration in terms of h and t in this question)
We are given 3 stages of movement of elevator. We'll first model them each of the stage one by one to find the height covered in each stage. After that we'll find the total height covered by adding heights covered in each stage, and equate it to Total height h. From that we can find the formula for acceleration.
<h3>
</h3><h3>
Stage 1</h3>
Constant acceleration, starts from rest.
Distance = 
Velocity = 
<h3>Stage 2</h3>
Constant velocity where
Velocity = 
Distance =
<h3>

</h3><h3 /><h3>Stage 3</h3>
Constant deceleration where
Velocity = 
Distance =

<h3>Total Height</h3>
Total height = y₁ + y₂ + y₃
Total height = 
<h3 /><h3>Acceleration</h3>
Find acceleration by rearranging the found equation of total height.
Total Height = h
h = 5a(t₁)²

Answer:
B
Explanation:
did this yesterday with my friend
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Answer: R = 394.36ohm
Explanation: In a LR circuit, voltage for a resistor in function of time is given by:

ε is emf
L is indutance of inductor
R is resistance of resistor
After 4s, emf = 0.8*19, so:





R = 394.36
In this LR circuit, the resistance of the resistor is 394.36ohms.