Posted by **Eliana ** on Friday, March 23, 2012 at 4:36am.

Playing in the street, a child accidentally tosses a ball at 21 m/s toward the front of a car moving toward him at 18 m/s. What is the ball's speed after it rebounds elastically from the car?

- physics! -
**Damon**, Friday, March 23, 2012 at 5:16am
In an elastic collision (1/2) m v^2 does not change.

21 m/s

- physics! -
**Philip**, Thursday, February 21, 2013 at 8:59pm
in the frame of the car, the ball comes in with 39 m/s speed, and bounces back at 39 m/s in the other direction. In the observer frame we need to add the 18 m/s relative speed of the car, and get 57 m/s

## Answer this Question

## Related Questions

- physics - a car is moving foward at 15.7m/s. a person in the bus throws a ball ...
- physics - A tennis ball with a speed of 12.5 m/s is moving perpendicular to a ...
- Physics - A tennis ball with a speed of 14m/s is moving perpendicular to a wall...
- college physics - A small ball of mass m is aligned above a larger ball of mass ...
- Physics - A soccer player kicks the ball toward a goal that is 23.0 m in front ...
- physics - A soccer player kicks the ball toward a goal that is 15.0 m in front ...
- physics - A soccer player kicks the ball toward a goal that is 15.0 m in front ...
- Physics - A soccer player kicks the ball toward a goal that is 27.0 m in front ...
- physics - A soccer player kicks the ball toward a goal that is 18.0 m in front ...
- Physics - A soccer player kicks the ball toward a goal that is 29.2 m in front ...

More Related Questions