krnhseya
Sep2-07, 03:47 PM
1. The problem statement, all variables and given/known data
A car P travles along a straight road with a constant speed v = 65mi/hr. At the instant when the angle theta = 60 degrees, determine the values of r (with dot above) in ft/sec and theta (with dot above) in deg/sec. (r = 100ft)
The picture has a car on highway and radius pointing diagonally from the origin which is on the field in "/" like this.
2. Relevant equations
Vr = r (with dot above)
Vtheta = r*theta(with dot above)
v = sqrt(((Vr)^2)+((Vtheta)^2))
3. The attempt at a solution
Vr = v cos theta and found Vr without a problem.
I tried to plug in v = 65mi/hr (converted to ft/sec) into 3rd eqn with Vr in order to find Vtheta. After that I substitude it into 2nd eqn since I know the radius. I got the theta value and converted to deg/sec from rad/sec but I am not getting answer.
What mistake have I made? :(
Thank you.
A car P travles along a straight road with a constant speed v = 65mi/hr. At the instant when the angle theta = 60 degrees, determine the values of r (with dot above) in ft/sec and theta (with dot above) in deg/sec. (r = 100ft)
The picture has a car on highway and radius pointing diagonally from the origin which is on the field in "/" like this.
2. Relevant equations
Vr = r (with dot above)
Vtheta = r*theta(with dot above)
v = sqrt(((Vr)^2)+((Vtheta)^2))
3. The attempt at a solution
Vr = v cos theta and found Vr without a problem.
I tried to plug in v = 65mi/hr (converted to ft/sec) into 3rd eqn with Vr in order to find Vtheta. After that I substitude it into 2nd eqn since I know the radius. I got the theta value and converted to deg/sec from rad/sec but I am not getting answer.
What mistake have I made? :(
Thank you.