- #1
- 33
- 0
Okay, so I thought I was on the right track with this problem, but clearly I haven't been getting the right answer!
The problem is as follows :
A physics instructor drives down to St. Louis to see his mom. Coming back, he drives the first half the distance at 65 km/hr and the second half of the distance at 100 km/hr. What is his average speed coming back from St. Louis ?
Okay, so I was trying to determine the t for the two distances and did the following work :
Well I was going to just post a scan of my work, but it says I can't so I'll just give some of what I did...
---
I used t=x/v to solve for the initial t and final t.
So... t initial = x initial / 65km/hr and t final = x final / 100km/hr
Then I plugged those into the equation for average velocity = change in x / change in t
So... V avg = (x - x initial) / [(x / 100) - (x initial / 60)]
---
I think I've gotten to the right point, but if the initial distance and final distance are the same I would just get zero, so I know I'm doing something wrong. Any help would be appriciated! :)
The problem is as follows :
A physics instructor drives down to St. Louis to see his mom. Coming back, he drives the first half the distance at 65 km/hr and the second half of the distance at 100 km/hr. What is his average speed coming back from St. Louis ?
Okay, so I was trying to determine the t for the two distances and did the following work :
Well I was going to just post a scan of my work, but it says I can't so I'll just give some of what I did...
---
I used t=x/v to solve for the initial t and final t.
So... t initial = x initial / 65km/hr and t final = x final / 100km/hr
Then I plugged those into the equation for average velocity = change in x / change in t
So... V avg = (x - x initial) / [(x / 100) - (x initial / 60)]
---
I think I've gotten to the right point, but if the initial distance and final distance are the same I would just get zero, so I know I'm doing something wrong. Any help would be appriciated! :)