Why does a ball move in your hand when net forces are 0?

The ball is still moving because there is no unbalanced force acting on it, so it will continue at a constant velocity. In summary, the net force on a ball in motion may be zero, but that does not mean all individual forces are zero. The ball will continue moving at a constant velocity due to the absence of unbalanced forces.
  • #1
Matt Poirier
This is a more general and probably silly question, but if you have a ball in your hand and you move it upwards, the acceleration will be positive then after you move it at constant velocity, acceleration will be 0. However, how is net force is 0 when the ball is still moving? You are clearly still pushing on the ball, so does your hand's push and air friction cancel so net force is 0?

<Moderator's note: Moved from a homework forum (general concept) and template removed.>
 
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  • #2
Matt Poirier said:
You are clearly still pushing on the ball, so does your hand's push and air friction cancel so net force is 0?
You forgot gravity, but yes, the net force being zero is not the same as all individual forces being zero, just the sum of them.
 

1. Why does a ball move in my hand if there are no net forces acting on it?

Even if there are no net forces acting on a ball, there may still be individual forces acting on it that cancel each other out. These forces can come from your hand, air resistance, or other objects that the ball may be in contact with, causing the ball to move.

2. How does Newton's First Law apply to a ball moving in my hand?

Newton's First Law states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force. In this case, the ball is initially at rest in your hand, but when you apply a force to it, it begins to move. However, when the forces on the ball are balanced, it will continue to move at a constant velocity or remain at rest.

3. Why does a ball stop moving when I release it from my hand?

When you release the ball from your hand, the force of your hand is no longer acting on it, but other forces such as air resistance and gravity are still acting on it. As these forces act on the ball, they cause it to slow down and eventually come to a stop.

4. How does the mass of the ball affect its movement when there are no net forces?

The mass of an object affects its motion by determining the amount of force needed to accelerate or decelerate it. In this case, when there are no net forces acting on the ball, the mass of the ball will determine how quickly it will come to a stop due to the forces acting on it, such as air resistance and gravity.

5. Can a ball move in my hand if there is no contact force present?

Yes, a ball can still move in your hand even if there is no contact force present. This is because there may be other forces acting on the ball, such as air resistance or friction, that can cause it to move without your hand physically pushing or pulling on it.

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