The discussion revolves around a physics problem involving impulse and momentum, specifically analyzing the force exerted by a wall on a ball during a collision. The ball has a mass of 0.15 kg and initial and final velocities of 5 m/s and 3 m/s, respectively, with a contact time of 0.1 seconds.
Participants are actively engaging with the problem, questioning their assumptions about velocity direction and the resulting force calculations. Some have proposed different interpretations of the signs in their calculations, leading to varying conclusions about the force's direction.
There is an ongoing discussion about the choice of positive and negative directions for velocity, which impacts the calculations. Participants are considering how these choices affect their understanding of the force exerted during the collision.
PhanthomJay said:Velocity and momentum are vectors, which means you have to take into account the direction of the velocities (plus or minus) before and after the collision. Your answer is not correct. If the force is negative, what does that imply?
um...12N toward the wall?PhanthomJay said:12 N for the average force is correct, but what is the direction of the 12 N force? You can choose any direction as negative, as long as you choose the opposite direction as positive. If you make the final velocity negative, then the initial velocity is positive. In which case,
0.1F = .15*(-3) - (.15*5)
F = - 12 N
How do you interpret the minus sign??