Conservation of Momentum Problem

AI Thread Summary
When the same horizontal force is applied to two objects of different masses on a frictionless surface, both objects experience the same change in momentum due to the force being applied for the same duration. Thus, the correct answer is that Object A and Object B have the same momentum after the push, as their initial momenta were both zero. The reasoning behind this is that the change in momentum (delta_p) for both objects is equal, given the same force and time. Option (b) is not plausible because it contradicts the established relationship between force, mass, and momentum. Therefore, the conclusion is that both objects end up with equal momentum after the force is applied.
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Homework Statement


The same horizontal force is applied separately to two objects initially at rest on a horizontal, frictionless surface. Object A has less mass than object B. In each case the force is applied for the same length of time. Which of the following statements is true after the push?

(a) Object A has greater momentum than object B.
(b) Object B has greater momentum than object A.
(c) Object A has the same momentum as object B.
(d) Object A has the same kinetic energy as object B.
(e) Both objects have no momentum.

Homework Equations


p = mv
delta_p = integral(F dt)

The Attempt at a Solution


The answer key solution to this problems is option c with the explanation that "since the both objects are given the same force over the same period of time, F = dp/dt , delta_pa = delta_pb."
However, why is delta_p(change in momentum) the same as momentum and why isn't option (b) a plausible answer?
 
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Avefan said:

Homework Statement


The same horizontal force is applied separately to two objects initially at rest on a horizontal, frictionless surface. Object A has less mass than object B. In each case the force is applied for the same length of time. Which of the following statements is true after the push?

(a) Object A has greater momentum than object B.
(b) Object B has greater momentum than object A.
(c) Object A has the same momentum as object B.
(d) Object A has the same kinetic energy as object B.
(e) Both objects have no momentum.

Homework Equations


p = mv
delta_p = integral(F dt)

The Attempt at a Solution


The answer key solution to this problems is option c with the explanation that "since the both objects are given the same force over the same period of time, F = dp/dt , delta_pa = delta_pb."
However, why is delta_p(change in momentum) the same as momentum and why isn't option (b) a plausible answer?
Both objects start at rest so the initial momentum of both is 0 (i.e. initial_p=0). So at any time, delta_p = current_p - initial_p = current_p - 0 = current_p
Of course, (c) contradicts (b), so (b) can not be true.
 
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