# Force required to destroy identical objects....

• KalStark
In summary: So, the energy required to destroy the object will be the same as if it was stationary, regardless of its velocity in another frame of reference. In summary, the amount of energy needed to destroy an object does not depend on its velocity in a specific frame of reference.
KalStark
...moving at different velocities?
Hi, I'm a college student who has just taken an interest in Physics and I was up all night yesterday thinking about this. Suppose you have two identical rock, boulder, mountain or whatever sized objects but one is moving at a extremely high velocity while the other is stationary. Would it take more energy to destroy that object given it's speed, or, since both objects are identical, would it not matter? I know it would take more energy/force to change the direction and velocity of the moving object but what about outright obliterating it?? And these are external forces btw...like a grenade or something like that...

KalStark said:
...moving at different velocities?
Hi, I'm a college student who has just taken an interest in Physics and I was up all night yesterday thinking about this. Suppose you have two identical rock, boulder, mountain or whatever sized objects but one is moving at a extremely high velocity while the other is stationary.
This is a meaningless statement since all motion is relative and you have not specified a frame of reference for either one, plus the fact that you could, for example, specify a frame of reference in which one of the objects is at rest OR you could choose a frame of reference in which the other object is at rest.

The amount of energy required to destroy something does not depend on the objects velocity. This is a result of the fact that an object moving at a high velocity in one frame of reference can be moving at a completely different velocity in another frame of reference. In its own frame of reference it is stationary.

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Ok, something like...a grenade, bomb, or any destructive device is set to explode when an object moving towards it from...1000 miles away at...20,000 mph...gets within an inch of reaching it. For the stationary object, that same
phinds said:
This is a meaningless statement since all motion is relative and you have not specified a frame of reference for either one, plus the fact that you could, for example, specify a frame of reference in which one of the objects is at rest OR you could choose a frame of reference in which the other object is at rest.
destructive device is launched/thrown at it.
Is that better?

Drakkith said:
The amount of energy required to destroy something does not depend on the objects velocity. This is a result of the fact that an object moving at a high velocity in on frame of reference can be moving at a completely different velocity in another frame of reference. In its own frame of reference it is stationary.
So, I'm just trying to wrap my head around this, say a spaceship is moving at near the speed of light. That spaceship would still be affected by missiles the same as any other ship?

KalStark said:
So, I'm just trying to wrap my head around this, say a spaceship is moving at near the speed of light. That spaceship would still be affected by missiles the same as any other ship?
You're not getting it. YOU, right now as you read this, are moving at near the speed of light. It's all a matter of what frame of reference you choose. I have chosen a frame of reference in which an "accelerated" particle at CERN is at rest and you are moving at near the speed of light.

phinds said:
You're not getting it. YOU, right now as you read this, are moving at near the speed of light. It's all a matter of what frame of reference you choose. I have chosen a frame of reference in which an "accelerated" particle at CERN is at rest and you are moving at near the speed of light.
Nah, I guess not. At least not yet. Are you saying that since everything can be put in a different frame of reference, speed is basically a non-factor as far as my question goes -- i.e the energy required to destroy the objects is the same?

KalStark said:
So, I'm just trying to wrap my head around this, say a spaceship is moving at near the speed of light. That spaceship would still be affected by missiles the same as any other ship?

The fact that the closing velocity between the missile and the ship is very, very high will make the damage MUCH more severe, but that's only because there is much more energy in the collision. For any given amount of damage done, the energy is always equal, regardless of whether the energy comes from an explosion, collision, etc.

Drakkith said:
The fact that the closing velocity between the missile and the ship is very, very high will make the damage MUCH more severe, but that's only because there is much more energy in the collision. For any given amount of damage done, the energy is always equal, regardless of whether the energy comes from an explosion, collision, etc.
So, the missile will still affect the ship same as any other but because of it's speed the damage it takes will be much higher?

KalStark said:
So, the missile will still affect the ship same as any other but because of it's speed the damage it takes will be much higher?

The simple answer is yes. Obviously real life is rarely simple.

KalStark said:
Nah, I guess not. At least not yet. Are you saying that since everything can be put in a different frame of reference, speed is basically a non-factor as far as my question goes -- i.e the energy required to destroy the objects is the same?
See Drakkith's post #3

phinds said:
This is a meaningless statement since all motion is relative and you have not specified a frame of reference for either one, plus the fact that you could, for example, specify a frame of reference in which one of the objects is at rest OR you could choose a frame of reference in which the other object is at rest.
I believe this statement is an unnecessary complication. Once the observer states that the objects move at different velocities.(with respect to a single reference frame: the observer's) Say a difference of 50m/s, this difference in their velocities would be constant, no matter the reference frame (unless we start considering near speed of light, which again, is unnecessary.)

abdullahi abass said:
I believe this statement is an unnecessary complication. Once the observer states that the objects move at different velocities.(with respect to a single reference frame: the observer's) Say a difference of 50m/s, this difference in their velocities would be constant, no matter the reference frame (unless we start considering near speed of light, which again, is unnecessary.)
I think you need to re-read the original problem statement, and perhaps Drakkith's post #3

A collision between two objects, let's name them A and B, will depend on their relative velocities, in fact it will depend on their relative speeds. This relative speed is the speed measured for B in A's inertial frame or the speed measured for A in B's intertial frame, which is the same.

The greater relative speed, the stronger impact, of course you would have to measure this relative speed just before the collision and you would have to take into account also the orientation (for example, in a car crash, a lateral impact is usually worse than a frontal impact) and probably other facts.

Hope it helps :).

## 1. What is the force required to destroy identical objects?

The force required to destroy identical objects depends on a variety of factors, including the strength and composition of the objects, the angle and direction of the force applied, and any external factors such as temperature or pressure. It is not a simple or straightforward answer, as each situation can be different.

## 2. Does the size of the object affect the force required to destroy it?

Generally, yes, the size of the object will affect the force required to destroy it. Larger objects tend to have more structural integrity and may require a greater force to break or destroy them.

## 3. Can the force required to destroy identical objects be calculated?

In some cases, the force required to destroy identical objects can be calculated using physics principles such as Newton's laws of motion. However, as mentioned earlier, there are many variables that can affect the force needed, so the calculation may not always be accurate.

## 4. Are there any materials that are particularly difficult to destroy?

Yes, there are certain materials that are known for their strength and resilience, making them difficult to destroy. For example, metals such as steel and titanium are often used in construction and engineering because of their high strength and durability.

## 5. Is it possible to destroy identical objects without using force?

In some cases, yes, it is possible to destroy identical objects without using force. This may be achieved through chemical reactions, such as dissolving an object in acid, or through natural processes such as erosion. However, these methods still involve some form of force, even if it is not a direct physical force applied by an external source.

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