SnowOwl18
Sep21-04, 02:27 PM
Hello, I was wondering if anyone could help me out with some of the problems from my problem set. I have tried to do the ones that I will post, but I keep coming out with the incorrect answers (according to the online scoring program that we use [CAP]).
***On a rainy day, raindrops fall with a vertical velocity of 8.4 m/s. If a car drives through the rain at 78.0 km/hr, what is the magnitude of the velocity of the raindrops relative to the car? At what angle are the raindrops falling relative to the car? Assume the direction the car is headed is 0o and down is 90o***
....so for this I drew a triangle with the 'vertical' side being 8.4m/s and the 'horizontal' as -21.7 m/s (after converting from km/hr to m/s). For the first part of the question, I just did vector subtraction to find the hypoteneuse and got -13.3 m/s...but apparently that was incorrect. And then for the angle I did -tan= (21.7m/s / 8.4m/s) and got 68.81 deg...but that was wrong too. What am I doing wrong here?
***An athlete executing a long jump leaves the ground at a 30.0o angle and travels 7.34m. What was the take-off speed?***
...I thought that maybe I was looking for an x-component here and tried to solve xcos30 = 7.34 ...but that didn't work either. I think I had the wrong idea here.
Anyway, those are just a few of the ones I'm struggling with. I know they are supposed to be easy questions...but I always tend to approach them the wrong way. Any help would be greatly appreciated. :o)
***On a rainy day, raindrops fall with a vertical velocity of 8.4 m/s. If a car drives through the rain at 78.0 km/hr, what is the magnitude of the velocity of the raindrops relative to the car? At what angle are the raindrops falling relative to the car? Assume the direction the car is headed is 0o and down is 90o***
....so for this I drew a triangle with the 'vertical' side being 8.4m/s and the 'horizontal' as -21.7 m/s (after converting from km/hr to m/s). For the first part of the question, I just did vector subtraction to find the hypoteneuse and got -13.3 m/s...but apparently that was incorrect. And then for the angle I did -tan= (21.7m/s / 8.4m/s) and got 68.81 deg...but that was wrong too. What am I doing wrong here?
***An athlete executing a long jump leaves the ground at a 30.0o angle and travels 7.34m. What was the take-off speed?***
...I thought that maybe I was looking for an x-component here and tried to solve xcos30 = 7.34 ...but that didn't work either. I think I had the wrong idea here.
Anyway, those are just a few of the ones I'm struggling with. I know they are supposed to be easy questions...but I always tend to approach them the wrong way. Any help would be greatly appreciated. :o)