
#1
Sep211, 03:29 PM

P: 1

1. The problem statement, all variables and given/known data
Physics: Only three variables and I don't know how to solve? here is one problem: Heather and Jerry are standing on a bridge 50 m above a river. Heather throws a rock straight down with a speed of 20 m/s . Jerry, at exactly the same instant of time, throws a rock straight up with the same speed. Ignore air resistance.  I need to find the time elapsed between the splashes. A rock is tossed straight up with a velocity of +20 m/s. When it returns, it falls into a hole 10m deep. I need to find velocity and time for the rock at the moment it reaches the bottom of the hole . For both of these I only have three variables, Velocity initial, change in X, and A. Should I assume that the V final is 0 in these?? otherwise I am confused. Thanks!! 2. Relevant equations all 5 standard kinematics 3. The attempt at a solution The questions is conceptual...currently i cannot attempt an answer as far as I know. 



#2
Sep211, 03:47 PM

P: 98

You have 3 variables, not including one variable that you want to find (work out what this one is first!) Then go through your 5 equations and use the one that includes all 4. You might have to do some rearranging!




#3
Sep211, 04:02 PM

HW Helper
P: 1,373

The first of your questions is easier than it looks, if you see the trick...



Register to reply 
Related Discussions  
Matlab Question: variables that depend on previous variables  Math & Science Software  5  
Complex conjugate variables as independent variables in polynomial equations  Linear & Abstract Algebra  0  
Angular Variables and Tangential Variables  Introductory Physics Homework  1  
how do you know if you should use 3 variables for 4 variables in IC design?  Electrical Engineering  2  
Solve for three variables with only two variables??  Introductory Physics Homework  8 