When a ball is thrown up in upward direction, it is said that force is in downward direction. Why we don't we consider the force given to the ball to throw up in the upward direction? Is there is no effect of the force given to the ball?
Answer
You should have a look at Newtons First Law of Motion:
"When viewed in an inertial reference frame, an object either remains at rest or continues to move at a constant velocity, unless acted upon by an external force."
When the ball is moving up and there is no force at all, then the ball will continue it's motion upwards. But when there is gravity, you should look at Newtons Second Law of Motion:
"The vector sum of the forces $F$ on an object is equal to the mass $m$ of that object multiplied by the acceleration vector $a$ of the object: $F = ma$."
While the ball is moving up, you do not interact with it, therefore the only force is gravity, accelerating the ball downwards (slowing it down).
You should not confuse the concept of force with the concept of energy. When throwing the ball up, you accelerate it and therefore you transfer kinetic energy to the ball, not giving it force.
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