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Please help me solve this:
A helicopter is travelling upward at a steady velocity of 5 metres per second,
when a parcel falls out of the door. 4.2 seconds later the percel hits the ground.
a)how high was the helicopter when the parcel fell out?
b)how high was the helicopter when the parcel hit the ground?
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This problem has a huge underwater stone, which a beginner student can miss.
It is in formulation initial conditions, what influence the governing equation.
The reader should take into account the fact that the initial velocity of the parcel is 5 m/s
vertically up, when it detaches from the helicopter.
Taking into account, that the initial velocity of the parcel is 5 m/s directed vertically upward,
the equation of the height as a function of time is
h(t) = -5t^2 + 5t + ,
where is the height of the helicopter, when the parcel detaches it (the unknown value under the first question).
We are given that the parcel got the ground 4.2 seconds after that. It gives us the equation to find
-5*4.2^2 + 5*4.2 + = 0.
From this equation, = 5*4.2^2 - 5*4.2 = 67.2 meters.
So, question (a) is just answered.
Question (b) is much simpler.
We simply should add the product 4.2*5 = 21 meter (the rise of the helicopter in 4.2 seconds) to
67.2 + 21 = 88.2 meters
to get the answer to question (b).
Solved.
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To see many other solved similar and different problems and to learn the subject deeper, wider and better, see the lessons
- Introductory lesson on a projectile thrown-shot-launched vertically up
- Problem on a projectile moving vertically up and down
- Problem on an arrow shot vertically upward
- Problem on a ball thrown vertically up from the top of a tower
- Problem on a toy rocket launched vertically up from a tall platform
Consider these lessons as your textbook, handbook, tutorials and (free of charge) home teacher.
Read them attentively and learn how to solve this type of problems once and for all.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this textbook under the topic "Projectiles launched/thrown and moving vertically up and dawn".
Save the link to this online textbook together with its description
Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson
to your archive and use it when it is needed.