A Coordinates and Interval Question

[jenn047]

Homework Statement

During a 4.95 s interval, a particle's coordinates change from x = 10.4 m, y = 4.95 m to x = 31.5 m, y = -4.95 m. Assuming the particle's velocity is constant, what will its coordinates be at the end of the next 4.95 s interval?

x= ____m
y= ____m

Homework Equations

The Attempt at a Solution

My first thought was to take the x and y's given and find y=mx+b however I'm not sure that it is relevant or even helpful.

Thanks.

 

[CompuChip]

You should consider both directions independently.

So x and y satisfy
x = u t + a,
y = v t + b

Equivalently, the distance covered in the second 4.95 seconds is the same as that covered in the first interval.

 

[jenn047]

CompuChip,

I'm not sure I understand what you're saying. What do the variables represent in your equations? I'm sorry if these are silly questions, however I just finished my second day of Physics and am completely new to it (and also very bad at it!).
Thanks.

 

[berkeman]

CompuChip is showing the equations of motion for a constant velocity. You can break the problem up into the orthogonal velocities in the x and y directions. So his first equation says that x(t) is equal to x(0) = a, plus an offset given by the velocity u multiplied by the time t.

Does that help?

 

[jenn047]

berkeman,

I understand that much, however I don't understand how those equations work with my numbers?

 

[berkeman]

berkeman,

I understand that much, however I don't understand how those equations work with my numbers?

You are given a delta-t and a delta-x and a delta-y. From those numbers and those equations, you can figure out what those constants are (u, a, v, b). With those constants and the next delta-t, you can figure out what the final positions will be after the second delta-t.

 

[jenn047]

Thank you, I appreciate your time!

 

[jenn047]

I definitely over analyzed the question. All you do is find the change in x and changed in y and add them to the last x and y coordinates. I didn't have to do anything with time or velocity.

 

[denverdoc]

In this case, yes, but what if the next interval was 6.1 seconds. Profs have bbeen known to do such things, esp physics profs!


So knowing the velocities is a necessary skill on the third day.