What is the speed of the ball after bouncing off an elastic surface?

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In an elastic collision, the speed of the ball after bouncing off a truck can be determined by considering the truck as an inertial reference frame. Since the truck's mass is significantly greater than the ball's, its speed remains effectively unchanged during the collision. The ball's incoming speed, as observed from the truck, is equal to the truck's speed minus the ball's throwing speed. After the collision, the ball's outgoing speed is the same as its incoming speed but in the opposite direction. Finally, to find the ball's speed after the bounce, add the truck's speed to the outgoing speed of the ball.
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Excuse me, but will anyone of u be kind enough to help me with this quetion----
Q.==== A truck is moving towards you with a velocity v. You throw a ball at it with velocity x, which bounces of elastically after hittin hthe truck. What is the speed of the ball now?
 
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Since no masses are given, this is a conceptiual, not mathematical question. The answer is very simple if you understand a few concepts.

First there is an assumption: the mass of the truck is so much greater than the mass of the ball that the speed of the truck effectively does not change during the collision. So, that means you can "observe" this collision from the point of view of the truck (it's an "inertial reference frame). The elastic collision form the truck's POV, is just like the ball bouncing (perfectly elastically) off a stationary wall.

What is the incoming speed of the ball as seen by the truck? What is the outgoing speed of the ball as seen by the truck? Add to that last speed, the speed of the truck's frame of reference.
 
No, I really do not know to play such note :smile: :smile: :smile: :smile: :smile:
 

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