An unstoppable object must have infinite acceleration: true or false?

Question

f=ma

Answer 1

Apart from the infinite mass case, here is another possibility:
a quantum particle whose position is known with some certainty. This means its velocity always has some uncertainty, so you can never say 'it has been stopped', so its unstoppable.

..i don't know if zero mass qualifies as an answer, as such a light particle may have to be treated quantum mechanically, so one cannot draw inferences using F = ma.

Answer 2

Clearly this is a false statement.

There are a couple of scenarios which contradict this statement.

As a previous respondent has said, infinite mass would render the object unstoppable.

The other scenario is a point "mass" of mass zero kilograms. No force can be applied to it at all, so therefore it is unstoppable....qed

Answer 3

False.

Acceleration is a change in velocity and would only be required to STOP the object (were it moving in the first place). Since this object is "unstoppable," though, no acceleration would be large enough to stop it, even an infinite one.

Answer 4

There is no such thing as 'unstoppable'
Some theoretical extremes are interesting
1. If 'a' tends to infinity (just assumption, not practically possible), 'f' tends to infinity (assumed 'unstoppable')
2. If 'm' tends to infinity, 'f' tends to infinity
m tends to infinity only when velocity of mass = velocity of light which is not achievable [theory of relativity]
3. Newton's first law of intertia
If the velocity of mass is infinity (not possible as mass velocity cannot be more than that of light], the mass inertia is infinity and it is not achievable.

Answer 5

I think F = dp/dt is more of an appropriate form of newton's second law to answer your question. Nevertheless it is nonsense, as such an object would violate conservation of momentum. Also in the object's reference frame, if its speed is lower than the speed of light, the object has zero velocity.

Answer 6

Hello =)

False...it could also have infinite mass....there is no such thing as any of the three, however.....

Namaste, and Happy New Year,

--Tom

Answer 7

As long as its acceleration will never approach zero.

Answer 8

Of course TRUE. If it can't be stopped, it must be moving.

Answer 9

In theory yes.

In practicle not yet done

Answer 10

only in space.