An object may appear to have one motion to one observer
depending on how the two observers are moving with respect to one another.
Imaging there is a river in the center of the screen (yelow dots are moving with water)
You can easily change frame of reference by moving your mouse to different regions.
If you move your mouse into the boat region,
You becomes on the boat watching other objects moving.
You can walk along with that person, or just standing there on the ground.
|frame of reference||Ground||Person||River||Boat|
|color code||Gray||Blue||dark Green||Red|
If you press with right mouse button, you need to click it again.
How to change the velocity vectors?
While the animation is suspended :
Click near the left leg of that person and drag the mouse up and down,
(The horizontal speed with respect to ground will increase due to river current)
Suggestion from Surendranath Reddy.B.:
Click the 2D checkbox and a ball will be thrown upward from the above moving object.
The trajectory of the ball(blue) will be shown for you.
I am now studying the Relative Motion applet, it is most interesting to see clearly the things we notice in everyday life.I have had some holidays boating on rivers and I can picture the effects clearly as I use the applet.While driving a boat it's speed relative to the current is most apparent, particulaly when trying to moor.
Thanks again for such an interesting web site
Best Wishes Ray Holloway email@example.com
I hope you enjoy playing with it.
Those numbers at the left side are object's horizontal coordinates,
Are you going to do it?
Typical Speeds (Some numbers are left blank for you to make a good quest, OK!¡^
|Motion||distance travels in one second||distance moves in one hour|
|Swimming sperm||45 um (=10-6m)||16.2 cm|
|snail||1.5 mm (=10-3m)||5.4 m|
|Flying bee||5 m||18 km|
|Running cheetah||29 m||104 km|
|Falcon in a dive||37 m||133 km|
|automobile(max.)||62 m||223 km|
|commercial jet airline||267 m||961 km|
|sound (in air)||340 m||1224 km|
|surface on the earth near equator||460 m||1.65 106 m|
Moon around the earth
3.6 106 m
|Earth around the Sun||29 km||1.04 108 m|
|Earth-Sun travel around ore galaxy||210 km||7.56 108 m|
|light||3 108 m||1.08 1012 m|
Your suggestions are highly appreciated! Please click firstname.lastname@example.org
Author¡GFu-Kwun Hwang, Dept. of physics, National Taiwan Normal University
Last modified :