Click Play to start the simulation. Enter the time when you think those two particle have the same HORIZONTAL speed. (Enter into the text field and the answer will be shown).
You can change the initial velocity for both particle with your mouse (drag the RED arrow).
The horizontal velocity for the top one should be larger than the lower one.
The top one will move with constant velocity, while the second will need to move up the hill (with constant deceleration a=-g*sin?)
You can also drag the yellow box to change the height of the slope.
Two traces shows X(t) for both particles.  Try to find out the answer from those two curves.



*** Remember: [color=red]You need to hit [b]ENTER[/b] after you enter the value[/color]. (the box turn yellow if you did not hit ENTER)

I hope you got the correct answer!  :)

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Enjoy the fun of Physics! You can access this simulation online from
Quiz: Do you know when two particles have the same horizontal speed?
Designed by Fu-Kwun Hwang (http://www.phy.ntnu.edu.tw/ntnujava/)
Deptartment of Physics, National Taiwan Normal University, Taiwan