Can a particle have zero acceleration when its velocity is zero?

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A particle can have zero acceleration when its velocity is zero, but acceleration can also be non-zero at that instant. When analyzing various combinations of velocity and acceleration, different scenarios arise: a particle can be moving east with increasing velocity (positive acceleration), moving east with decreasing velocity (negative acceleration), or moving with constant velocity (zero acceleration). In contrast, a particle can also be moving west with increasing or constant velocity, or at rest with either positive or negative acceleration. The discussion emphasizes that while acceleration can be zero when velocity is zero, it is not a strict requirement if considered over an instant. Understanding these concepts is crucial for grasping the dynamics of motion.
mini_smurf13
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1) If the velocity of a particcle is zero, can its acceleration be zero? Explain.

2) Consider the floowing combinations of signs and values for velocity and accleration of a particle with respect to a one-dimensional x axis.

Velocity | Acceleration
  1. + | +
  2. + | -
  3. + | 0
  4. - | +
  5. - | -
  6. - | 0
  7. 0 | +
  8. 0 | -

Describe what a particle is doing in each case, and give a real-life example for an automobile on an east-west one dimensional axis, with east considered the positive direction.​

I do not understand this at all! Please please please please help if you can with as much as you can. ANY help will be greatly appreciated because I have no idea what to do. :confused:
 
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If the velocity of a particle is zero, it's acceleration must be zero. Backwards: if the acceleration of a particle is zero, it's velocity can either be zero or constant.
 
Alright for question 2 in the first scenario the particle is traveling east and it's velocity is increasing as acceleration is positive. In the second the particle is once more traveling east but it's velocity is decreasing as acceleration is negative. In the third it is traveling east with constant velocity and fourth traveling west with increasing velocity.
Can you begin to get the idea? Hopefully that helps.
 
BTW, must acceleration be zero when at that INSTANT the velocity is zero?
i think no, there can be acceleration when velocity is zero, but when the period of Zero Velocity stretchs for more that an "instant". then yes, acceleration must be zero.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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