related rates

Sara.H said:
View attachment 21798 please help me for solve this problem.
Click to expand...

Sara.H, do not post your problem in someone else's thread. Go back to the
top of the "Calculus" section and start your own thread with a subject line.
Also, please post what work you have contributed toward the problem .....................................(moved problem as suggested)
 
Sara.H said:
View attachment 21798 please help me for solve this problem.
Click to expand...
If I were to do this problem, I would sketch putting the cars at the origin and one would travel negative x direction (west) and the other would travel negative y direction (south). Now define the speeds as dx/dt and dy/dt and the distance between those cars at anytime 't' would be r(t).

Please show us what you have tried and exactly where you are stuck.

Please follow the rules of posting in this forum, as enunciated at:


Please share your work/thoughts about this problem.
1600719574455.png
 
First, write the distance the south moving car is from the original point in terms of time, t. Second write the distance the west moving car is from the original point in terms of time, t. Third write the distance between the two cars in terms of time, t (hint: Pythagorean theorem). Finally differentiate that with respect to t to get a rate.
(The arithmetic turns out to be surprisingly simple!)
 
HallsofIvy said:
First, write the distance the south moving car is from the original point in terms of time, t. Second write the distance the west moving car is from the original point in terms of time, t. Third write the distance between the two cars in terms of time, t (hint: Pythagorean theorem). Finally differentiate that with respect to t to get a rate.
(The arithmetic turns out to be surprisingly simple!)
Click to expand...
Yes - 122 + 52 = 132
 
HallsofIvy said:
First, write the distance the south moving car is from the original point in terms of time, t. Second write the distance the west moving car is from the original point in terms of time, t. Third write the distance between the two cars in terms of time, t (hint: Pythagorean theorem). Finally differentiate that with respect to t to get a rate.
(The arithmetic turns out to be surprisingly simple!)
Click to expand...
 

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Now use the equation you had derived. After 2 hrs:

x = ?

y = ?

r = ?

dx/dt = ?

dy/dt = ?

Now calculate dr/dt = ?
 
Sara.H said:
I don't know x and y
Click to expand...
Subhotosh Khan said:
If I were to do this problem, I would sketch putting the cars at the origin and one would travel negative x direction (west) and the other would travel negative y direction (south). Now define the speeds as dx/dt and dy/dt and the distance between those cars at anytime 't' would be r(t).
Click to expand...
Did you read the above (response #3)?
 
Sara.H said:
This problem has not given us an x and y.
Click to expand...
However, it did give you data using which you can calculate x and y.

Read the problem again.

How long (time) after starting, we need to measure distance?

What are the respective speeds of each car? What is the equation that combines constant speed, distance and time?

Now I ask again:
Subhotosh Khan said:
x = ?

y = ?
Click to expand...
 
Subhotosh Khan said:
However, it did give you data using which you can calculate x and y.

Read the problem again.

How long (time) after starting, we need to measure distance?

What are the respective speeds of each car? What is the equation that combines constant speed, distance and time?

Now I ask again:
Click to expand...
ok is it mean that x=120 and y=50?
 
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