Two bodies, A and B, collide as shown in Figures I and II below. Which statement is true?
A) They exert equal and opposite forces on each other in I but not in II.
B) They exert equal and opposite force on each other in II but not in I.
C) They exert equal and opposite force on each other in both I and II.
D) The forces are equal and opposite to each other in I, but only the components of the forces parallel to the velocities are equal in II.
E) The forces are equal and opposite in I, but only the components of the forces perpendicular to the velocities are equal in II

Question

Two bodies, A and B, collide as shown in Figures I and II below.  Which statement is true?
A) They exert equal and opposite forces on each other in I but not in II. 
B) They exert equal and opposite force on each other in II but not in I. 
C) They exert equal and opposite force on each other in both I and II. 
D) The forces are equal and opposite to each other in I, but only the components of the forces parallel to the velocities are equal in II. 
E) The forces are equal and opposite in I, but only the components of the forces perpendicular to the velocities are equal in II

Quizplus · Accepted Answer

According to Newton's Third Law of Motion, for every action, there is an equal and opposite reaction. Therefore, in both figures, bodies A and B exert equal and opposite forces on each other. Choice A and B are incorrect because they state that the equal and opposite forces only happen in one of the figures. Choice D and E are incorrect because they refer to components of forces that are not mentioned in the question or depicted in the figures.

Two Bodies, a and B, Collide as Shown in Figures