Projectile Motion: Is Final Y Velocity Lower Than Initial? Impact on Time?

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SUMMARY

The discussion centers on the relationship between final and initial y velocity in projectile motion and its impact on time until impact. It is established that while an object's final y velocity can indeed be lower than its initial y velocity due to downward acceleration, this does not directly correlate with an increase in time until the object hits the ground. Instead, the kinematics equations, which account for acceleration, should be utilized rather than the simplistic equation x/v = t. The key takeaway is that instantaneous speed in projectile motion is always affected by gravitational acceleration, leading to a decrease in velocity over time.

PREREQUISITES
  • Understanding of kinematics equations in physics
  • Knowledge of projectile motion concepts
  • Familiarity with the effects of gravitational acceleration
  • Basic algebra for manipulating equations
NEXT STEPS
  • Study the kinematics equations for projectile motion
  • Explore the concept of instantaneous vs. average speed
  • Research the effects of gravitational acceleration on motion
  • Practice solving projectile motion problems with varying initial velocities
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Students studying physics, educators teaching projectile motion, and anyone interested in understanding the dynamics of motion under gravitational influence.

Nerdyboy
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I was solving a projectile motion problem and was wondering if, while going downwards, an object's final y velocity can be less than the initial y velocity. If this is true, would this change the time until it hit the ground?

The only reason I was thinking about this is because if x/v = t. If v is smaller, doesn't time increase?
 
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I believe you are talking about two different ideas: average speed and instantaneous speed. Yes, it velocity is lower than time must be larger in the equation you listed... but that is the average distance in (distance)/(velocity)=time. Instantaneous speed in projectile motion must ALWAYS be less than it was to start with, because there is downward acceleration on earth. This acceleration decreased velocity, but you don't use x/v=t... rather, you used the kinematics equations which take acceleration and such into account.
 

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