Displacement and Velocity Question

In summary, the conversation discusses a physics problem involving an object moving in a straight line and its velocity at a given time. The displacement at time t is given as -6t6-4t4+2 and the question asks for the velocity at t=7 to the nearest whole number. The answer is calculated to be -610540, but the question's request for the nearest whole number seems odd. It is suggested to just move on and submit the answer with confidence. The conversation also mentions the possibility of different data values for each candidate in a computer quiz. Overall, the conversation provides helpful insights and reassurance for solving the problem.
  • #1
cosmictide
37
0
Hi guys,

Would really appreciate your thoughts on the question below.

Homework Statement



An object moves in a straight line and its displacement s at time t is given by -6t6-4t4+2. What is the velocity of the object at time t=7? Give the answer to the nearest whole number.

The Attempt at a Solution



I calculated the answer as being -610540. However, the question asks to give the answer to the nearest whole number and to me that seems absurd unless I have the wrong answer of course. Would really appreciate if someone could check my answer and let me know if it's correct or not.

Thanks in advance. :smile:
 
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  • #2
Usually on this site people are really finicky about not giving away answers, but this is a simple enough problem, and your answer looks good anyway.

It's good to cross reference your answer with the question, but depend on that too much and you're going to stress yourself to death.
 
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  • #3
cosmictide said:
Hi guys,

Would really appreciate your thoughts on the question below.

Homework Statement



An object moves in a straight line and its displacement s at time t is given by -6t6-4t4+2. What is the velocity of the object at time t=7? Give the answer to the nearest whole number.

The Attempt at a Solution



I calculated the answer as being -610540. However, the question asks to give the answer to the nearest whole number and to me that seems absurd unless I have the wrong answer of course. Would really appreciate if someone could check my answer and let me know if it's correct or not.

Thanks in advance. :smile:
That answer looks good.
 
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  • #4
chatsash said:
Usually on this site people are really finicky about not giving away answers, but this is a simple enough problem, and your answer looks good anyway.

It's good to cross reference your answer with the question, but depend on that too much and you're going to stress yourself to death.

Oh okay, I have no problem showing all my working as to how I arrived at the said answer. Like you said it's a simple problem but I don't understand why the question asks to give the answer to the nearest whole number?

Surely it seems absurd to round such a large negative integer to zero? Is it just me or isn't that kind of odd? Unless of course I've managed to get the wrong answer. :smile:
 
  • #5
SammyS said:
That answer looks good.

Thanks Sammy. :smile:

I'm more confused on why the question wants me to give the answer to the nearest whole number. Surely it's kind of absurd to round such a high negative integer to zero?
 
  • #6
Don't worry about it too much. A lot of these questions are reworked from old examples, and have just had their exponents, conditions, and coefficients changed. Maybe at one point they used t=2.5? Either way, when you're confident in your answer, it's best to just move on.
 
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  • #7
chatsash said:
Don't worry about it too much. A lot of these questions are reworked from old examples, and have just had their exponents, conditions, and coefficients changed. Maybe at one point they used t=2.5? Either way, when you're confident in your answer, it's best to just move on.

It's actually a computer quiz which counts towards my final grade. I only get 1 attempt at the answer so if the answer is incorrect I don't get the marks lol.
 
  • #8
cosmictide said:
An object moves in a straight line and its displacement s at time t is given by -6t6-4t4+2. What is the velocity of the object at time t=7? Give the answer to the nearest whole number.
It is unsual in physics for data to be given without appropriate units. It would not surprise me to hear that the intended question involved somethng more than plain 7 nothing, and the rest of the text has somehow been lost, e.g. 7.1 seconds.

Edit: Oh, it's a cmputer quiz. Likely they dropped the units in the interest of simplicity, then.

Note: some computer quizzes use different data values for each candidate, to counter cheating by copying. So you got those coefficents, but others may have seen coefficients that included some fractions.
 
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  • #9
NascentOxygen said:
It is unsual in physics for data to be given without appropriate units. It would not surprise me to hear that the intended question involved somethng more than plain 7 nothing, and the rest of the text has somehow been lost, e.g. 7.1 seconds.

Edit: Oh, it's a cmputer quiz. Likely they dropped the units in the interest of simplicity, then.

Note: some computer quizzes use different data values for each candidate, to counter cheating by copying. So you got those coefficents, but others may have seen coefficients that included some fractions.

It's part of a computer quiz so the units are usually left out. I think as you said the question is most likely a rewrite of a similar question but with a decimal value for t. I will just submit the negative integer value I obtained and hope for the best.
 

1. What is displacement and how is it different from distance?

Displacement refers to the shortest distance between an initial and final position. It takes into account the direction of movement and can be either positive or negative. Distance, on the other hand, refers to the total length traveled and does not consider direction.

2. How is displacement calculated?

Displacement is calculated by subtracting the initial position from the final position. It can be represented by the symbol "Δx" or "d". The formula for displacement is Δx = xf - xi, where xf is the final position and xi is the initial position.

3. What is velocity and how is it related to displacement?

Velocity is a measure of the rate of change of displacement over time. It takes into account both the magnitude and direction of displacement. It is calculated by dividing the displacement by the time taken. The formula for velocity is v = Δx / t, where v is velocity, Δx is displacement and t is time.

4. What is the difference between average velocity and instantaneous velocity?

Average velocity is the total displacement divided by the total time taken. It gives an overall picture of the motion. Instantaneous velocity, on the other hand, refers to the velocity at a specific point in time. It is calculated by taking the limit as the time interval approaches zero in the formula for average velocity.

5. How does acceleration affect displacement and velocity?

Acceleration is the rate of change of velocity over time. It can either be positive or negative, depending on whether the velocity is increasing or decreasing. Acceleration affects displacement by changing the magnitude and direction of the displacement. It affects velocity by changing the rate at which the displacement is changing.

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