Meaning of a phrase in a kinematics problem

In summary, the problem asks for the vertical displacement of an object that is thrown horizontally with an initial speed of 10 m/s after 4 seconds of flight, assuming negligible air resistance. This is represented by the equation Δy = v0y.t + 1/2(-g)t2, where v0y = 0.
  • #1
Fabrizio Vassallo
17
6
1. Problem statement:

"An object is thrown horizontally with an initial speed of 10 m/s. How far will it drop in 4 seconds?"

Homework Equations



Δx = v0x.t
Δy = v0y.t + 1/2(-g)t2

The Attempt at a Solution


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When I first read it, I thought that 'how far' means Δx, since when someone says 'how far did you throw the ball' you would usually answer something like 'I threw it like 10 yards', and that is referring to Δx. However, the Princeton book says that when asked 'how far' it means Δy instead, so I would like to know if anyone here has a way to explain me what I am not understanding, or, if it corresponds, clarify that the book whether the book is wrong.
For more context, I'm preparing for the SAT Subject Test in Physics. I'm from Argentina, so I do not speak English as my main language, and this might be why I'm confused. The book I refer to is the Princeton Review's 'Cracking the SAT Subject Test in Physics' one (16th edition).

Thank you in advance to anyone who replies!
 
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  • #2
The object will drop just as much as it would when dropped without any initial velocity in the x-direction. The ##v_{0y} = 0## here, because it's said that the object is thrown horizontally. Note that the problem assumes that air resistance is negligible.
 
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  • #3
"How far" is ambiguous in a physics problem statement. That's why you should always find it qualified. In this instance the qualifier is "will it drop". So "how far will it drop" should be interpreted as a vertical displacement.
 
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  • #4
hilbert2 said:
The object will drop just as much as it would when dropped without any initial velocity in the x-direction. The ##v_{0y} = 0## here, because it's said that the object is thrown horizontally. Note that the problem assumes that air resistance is negligible.
The OP is not asking how to solve the problem, he is asking about the interpretation of the problem statement (language use).
 
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  • #5
hilbert2 said:
The object will drop just as much as it would when dropped without any initial velocity in the x-direction. The ##v_{0y} = 0## here, because it's said that the object is thrown horizontally. Note that the problem assumes that air resistance is negligible.
Thank you for your answer. Thankfully, I was able to understand how to solve these kind of problems. My only issue was about what the problem was asking me to figure out.
gneill said:
"How far" is ambiguous in a physics problem statement. That's why you should always find it qualified. In this instance the qualifier is "will it drop". So "how far will it drop" should be interpreted as a vertical displacement.
Thank you, seriously! From now on, I will only pay attention to what it says after 'how far' to interpret what the statement is asking me to do, since the use of this phrase sounds kind of tricky to me!
 
  • #6
Fabrizio Vassallo said:
"How far will it drop in 4 seconds?"

The key word is "drop". In this context, this almost always means "fall vertically downwards."

Edit: didn't notice @gneill's previous response.​
 
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  • #7
George Jones said:

The key word is "drop". In this context, this almost always means "fall vertically downwards."​
Thank you very much for your answer. From now on, I will try to look for the qualifier, as the previous comment said, because the 'how far' sounds a little bit tricky to me so far!
 

1. What is the meaning of a phrase in a kinematics problem?

The meaning of a phrase in a kinematics problem refers to the specific wording or terminology used to describe the problem. This can include terms such as "displacement," "velocity," "acceleration," and "time." Understanding the meaning of these phrases is crucial in solving kinematics problems and understanding the motion of objects.

2. Why is it important to understand the meaning of a phrase in a kinematics problem?

Understanding the meaning of a phrase in a kinematics problem is important because it helps to accurately interpret the information given in the problem and determine the correct equations and calculations needed to solve it. Without a clear understanding of the meaning of these phrases, it can be difficult to solve kinematics problems correctly.

3. Are there any common misconceptions about the meaning of phrases in kinematics problems?

Yes, there are some common misconceptions about the meaning of phrases in kinematics problems. For example, many people confuse velocity and acceleration, but they are two distinct concepts. Velocity refers to the rate of change of an object's displacement, while acceleration refers to the rate of change of an object's velocity.

4. How can I improve my understanding of the meaning of phrases in kinematics problems?

To improve your understanding of the meaning of phrases in kinematics problems, it is important to familiarize yourself with the basic concepts and equations used in kinematics. Practice solving various types of problems and pay close attention to the wording and meaning of each phrase. You can also seek help from a teacher or tutor if you are struggling to understand the concepts.

5. How can I apply my understanding of the meaning of phrases in kinematics problems to real-world situations?

Understanding the meaning of phrases in kinematics problems can help you analyze and solve real-world situations involving motion. For example, if you know the initial velocity and acceleration of a car, you can use kinematics equations to determine its final velocity and how long it will take to reach a certain distance. This can be useful in fields such as engineering, physics, and transportation.

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