Acceleration (short question, but not so simple)

Think of air resistance.
Opposite the direction of motion.

 

ok
but when the ball is going up the air resistance is downward and the force on the ball is
- mg - R
and when the ball is coming down the air resistance is upward hence resultant force on the ball is - mg + R

 

its easy...when the ball is thrown upwards the resultant force acting on it is the same as when is is falling down... meaning having the same acceleration...but due to gravity pull from the earth acceleration increases when it falls therefore the answer is.... the acceleration is faster when the ball falls

 

therefore wat is ur answer???

 

When the ball is released from your hand, the acceleration is constant until it hits the ground. As far as if it takes greater acceleration to throw the ball "a lot higher than your own height," that just depends on how tall you are and where you release it.

 

sorry, I thought it that way. Can't get meaning of under the through.

 

The key words are that the ball reaches a lot higher than your own height.
The ball reaches an upward velocity during you keep it. Its displacement can not be longer than twice the length of your arm, and that is a bit shorter than your height. It accelerates form zero velocity to v during a displacement h. You know the relation between acceleration, displacement and final velocity?
When you release the ball it has got the upward initial velocity v and it rises to height H, when its velocity becomes 0. You can use the same formula among magnitude of acceleration (it is g now) height and initial velocity that you used before for the final velocity.
H >>>h. Can you go ahead?

 

No. Your formula is wrong. Just check the units.

ehild