Answer:
a) 
b) 
Explanation:
Given:
- mass of the ball thrown up,
- initial velocity of the ball thrown up,
- height above the ground from where the ball is thrown up,
a)
Maximum height attained by the ball above the roof level can be given by the equation of motion.
As,
where:
final velocity at the top height of the upward motion 
acceleration due to gravity
height of the ball above the roof
Now,
Therefore total height above the ground:
b)
Now we find the time taken in raching the height 
:
final velocity at the top of the motion
So,
Now the time taken in coming down to the ground from the top height:
where:
is the initial velocity of the ball in course of coming down to ground from the top
Here the direction acceleration due to gravity is same as that of motion so we are taking them positively.
Therefore the total time taken in by the ball to hit the ground after it begins its motion:
The apparent change is the Doppler shift
The answer is B. A frame of reference that is accelerating.
A constant velocity means the acceleration is zero.
Engineering controls could involve altering the weight of the products, adjusting the heights of the work surfaces, or getting lifting equipment. Administrative controls are workplace policies, practices, and processes that reduce the likelihood of risky situations for employees.
<h3>What are Engineering controls?</h3>
- Engineering controls are methods for preventing dangerous situations for workers by erecting a barrier between them and the danger or by ventilating the area to remove any hazardous materials.
- Instead of depending on employee behavior or mandating that employees wear safety gear, engineering controls entail making physical changes to the workplace itself.
<h3>What is Administrative controls?</h3>
- Administrative controls are policies, procedures, shift designs, or training that reduce the threat of a hazard to a person.
- Typically, administrative controls aim to alter people's behavior (such as that of manufacturing workers) rather than eliminating the real risk or provide personal protective equipment (PPE).
Learn more about Administrative controls here:
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