Two cars, A and B, start from the same place. A take the direction of the north with a constant velocity of 80 km/h, and B the direction of the east, with an acceleration of 4 m/s2 (start from the rest). After 13 seconds, which is the relative velocity of the car A in reference to B?
Solution with FisicaLab
Erase the content of the chalkboard. And add one element Mobile in X, one element Mobile in Y with constant velocity, one element Relative velocity, and one element Stationary reference system. As show the image below:
We assume that the car A take the direction of the positive Y axis, and car B the direction of the positive X axis. And that both cars start from the origin. Now, as we know the end time, in the element Stationary reference system, write:
To the element Mobile in Y with constant velocity, we call this car Car A, write:
80 @ km/h
To the element Mobile in X, we call this car Car B:
And to the element Relative velocity:
Where the magnitude and the angle of the relative velocity are unknown data. Now click in the icon Solve to get the answer:
v = 56.549 m/s ; ang = 156.861 degrees ; xf = 338.000 m ; vxf = 52.000 m/s ; yf = 288.889 m ; Status = success.
The desired data are v = 56.549 m/s and ang = 156.861 degrees.