Some confusion about balanced forces

In summary, the force from the ground must be greater than the weight of the object to stop its motion. This extra force comes from the collision of the object with the ground and the material structure of the ground allowing it to resist movement. The forces are only equal under certain circumstances, such as when the object is no longer accelerating.
  • #1
ViolentCorpse
190
1
Hi,

My question is:

1)When an object falls to the ground, shouldn't the ground exert a force greater than the weight of the object to stop its motion altogether? Because if the forces experienced by the object the moment it strikes the ground are equal and opposite in direction, then that should only stop the object from accelerating further and it should continue moving with the velocity it had the instant before the forces cancelled. (I know it sounds silly for the ground because it's a solid, rigid body and can not allow the object to continue its motion through it. Maybe it'd be better if you replace the ground with a trampoline and explain it for that? )

Thank you for your time. :)
 
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  • #2
ViolentCorpse said:
Hi,

My question is:

1)When an object falls to the ground, shouldn't the ground exert a force greater than the weight of the object to stop its motion altogether? Because if the forces experienced by the object the moment it strikes the ground are equal and opposite in direction, then that should only stop the object from accelerating further and it should continue moving with the velocity it had the instant before the forces cancelled.
Your thinking is quite correct. In order to stop the object, the force from the ground must be greater that the object's weight. (At least for some time.)

Why do you think that is a problem?
 
  • #3
Doc Al said:
Your thinking is quite correct. In order to stop the object, the force from the ground must be greater that the object's weight. (At least for some time.)

Why do you think that is a problem?

Oh, I'm sorry I didn't make myself clear enough.

The problem is, I don't understand where that greater force comes from.

According to my understanding, The forces on the object are gravity (downward force) and the normal force of the ground (upward) and I think they are equal. But as you just confirmed, the normal force must be greater than that with which gravity is pulling the object. I'm just unable to pin down where that extra normal force is coming from.

Thank you for your prompt reply, Doc Al!
 
  • #4
ViolentCorpse said:
According to my understanding, The forces on the object are gravity (downward force) and the normal force of the ground (upward) and I think they are equal.
They are only equal under certain circumstances. Such as when the object is no longer accelerating.
I'm just unable to pin down where the normal force is getting that extra force from.
That "extra" force comes from the collision of the moving object with the ground. The material structure of the ground allows it to resist the movement of the object by exerting an upward force on it.
 
  • #5
Doc Al said:
They are only equal under certain circumstances. Such as when the object is no longer accelerating.

That "extra" force comes from the collision of the moving object with the ground. The material structure of the ground allows it to resist the movement of the object by exerting an upward force on it.

Hm. I see.

Thank you for your help! I appreciate it a lot. :)
 

1. What are balanced forces?

Balanced forces are forces that are equal in size and opposite in direction. This means that when two or more forces act on an object, they cancel each other out and the object remains either at rest or in constant motion.

2. How do you know if forces are balanced?

To determine if forces are balanced, you can use the principle of vector addition. If the sum of all forces acting on an object is zero, then the forces are balanced. Additionally, if an object is not accelerating, it is likely experiencing balanced forces.

3. Can balanced forces cause motion?

No, balanced forces do not cause motion. As mentioned earlier, they result in an object remaining at rest or in constant motion. In order for an object to accelerate, there must be an imbalance of forces, known as unbalanced forces.

4. Are balanced forces always present?

Yes, balanced forces are always present in a system where at least two forces are acting on an object. This is because forces always occur in pairs and they must be balanced in order for the object to remain in equilibrium.

5. What is the significance of balanced forces in everyday life?

Understanding balanced forces is important in everyday life because it helps us explain and predict the behavior of objects. For example, it explains why objects remain at rest or in motion, and why objects don't accelerate when multiple forces are acting on them. This knowledge is also crucial in fields such as engineering and physics.

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