My Physics Teacher Must Really Hate Pianos

In summary, a 350 kg piano is dropped from a stationary helicopter and as it falls, its acceleration is affected by air resistance. At the moment that the air resistance exerts an upward force of 1400 N, the piano's acceleration is found to be 5.8 m/s2, which is less than the force of gravity. This is confirmed by using the equation a = (mg - F)/m. It is important to do the algebra first before substituting in numbers to ensure accuracy.
  • #1
Medgirl314
561
2

Homework Statement



A 350 kg piano is dropped from a stationary helicopter. As it falls, it picks up speed and the air resistance increases, causing its acceleration to be less than 9.8 m/s2 What is the piano's acceleration at the moment that the air resistance is exerting an upward force of 1400 N?



Homework Equations


w=mg


The Attempt at a Solution



a=w-fair /m

w=mg
w= 350 kg*9.8 m/s2
w=3430 N
a=3400-1400 N / 350 kg
a=2030/350 kg =5.8 m/s2

This is less than the force of gravity, ans seems reasonable. Could someone confirm?

Thanks!
 
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  • #2
a=3400-1400 N / 350 kg
... so like the other one, you should do the algebra before you start using numbers then it is easier to see what is going on.

F = air resistance, mg = weight, and a is the acceleration ... then,
draw a free body diagram and picking down as positive:

mg-F=ma means that a=(mg-F)/m ...

... putting the numbers in now gets you the same thing ... but now you can tell if it is right or not because the setup and the algebra are all there without the numbers to hide things.
 
  • #3
Thanks! I didn't have to mess with the equation too much, because my teacher had a similar one in an example. I usually find it harder to do the algebra first, but I can try it and see if it's easier in the end. Thank you!
 
  • #4
Yah - if you just copy the examples, it'll bite you in the long run.
It takes a bit to get used to moving the variables around, but it pays off.
 
  • #5
Thanks for the help! :smile:
 

1. Why does the title say "My Physics Teacher Must Really Hate Pianos"?

The title is meant to be a humorous play on words. It is a common saying that someone "hates" something when they are bad at it or struggle with it. In this case, the person in the title is implying that their physics teacher is not good at understanding or teaching the concept of pianos.

2. What does a physics teacher have to do with pianos?

Physics and music are closely related, as sound is a physical phenomenon that can be explained through the principles of physics. Therefore, a physics teacher may use examples from music, such as pianos, to help students understand and apply physics concepts.

3. Is this about a specific teacher or just a general statement?

The title is meant to be a general statement and not about any specific teacher. It is simply a humorous way of expressing the idea that someone struggles with or dislikes a certain topic, in this case, pianos.

4. Can a physics teacher actually dislike pianos?

It is possible for a physics teacher to dislike pianos as a personal preference, but it is unlikely that they would hate them in the literal sense. As mentioned before, music and physics are closely related, so it is more likely that a physics teacher would use examples from music, including pianos, to teach concepts rather than dislike them.

5. How does this relate to being a scientist?

As a scientist, it is important to have a broad understanding of various subjects, including physics and music. This title highlights the connection between the two and the role that a physics teacher plays in explaining and teaching these concepts to students.

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