Elementary questions relating to Newton's laws of motion

[chipotleaway]

i) If a wall breaks when it gets hit by a cannonball, did the wall exert an equal and opposite force on the cannonball?

ii) Would the force exerted by the cannonball on the wall only be the amount that was needed to break it?

iii) Hypothetically, is it possible for the wall to break but also cause the cannonball to rebound?

 

[Doc Al]

i) If a wall breaks when it gets hit by a cannonball, did the wall exert an equal and opposite force on the cannonball?

ii) Would the force exerted by the cannonball on the wall only be the amount that was needed to break it?

iii) Hypothetically, is it possible for the wall to break but also cause the cannonball to rebound?

Good questions. What do you think?

 

[chipotleaway]

Good questions. What do you think?

i) I think it does and

ii) I also think that the reaction force from the wall would be equal to the force needed to break it. Like if you were to drop a bowling ball on a table, the table wouldn't feel the entire weight of the ball before it broke (assuming the strength is less than the weight of the ball)

iii) Hmm...the wall would have to have sufficient strength to exert a reaction force big enough to change the momentum of the cannonball...I'll try to work out the details later, heh.

 

[faldahlawi]

To answer your question, I would think about impulse. The longer you exert a force, the greater the momentum. So to break the wall, the cannonball need to exert some amount of force for a period of time. Then, once the wall break and rocks flies in every directions, it's a work problem (force times displacement). Hence, the wall does exert the same force back but not enough impulse to stop the cannonball.

 

[PJC01]

i) According to Newton's third law of motion, for every action, there is an equal and opposite reaction. Therefore, if the wall breaks when hit by a cannonball, the wall must have exerted an equal and opposite force on the cannonball. This is because the cannonball and the wall are interacting with each other, and the forces they exert on each other are equal in magnitude and opposite in direction.

ii) No, the force exerted by the cannonball on the wall would not only be the amount needed to break it. The cannonball will exert a force on the wall that is equal to its mass multiplied by its acceleration, according to Newton's second law of motion. This force may be greater than the force needed to break the wall, resulting in the wall breaking and the cannonball continuing to move forward with its remaining force.

iii) Hypothetically, it is possible for the wall to break and also cause the cannonball to rebound. This would occur if the wall exerts a force on the cannonball that is greater than the force needed to break it, causing the cannonball to bounce off the wall with some remaining force. However, this would depend on the specific circumstances and forces involved, as well as the strength and composition of the wall.