Why does increasing mass also increase kinetic energy and velocity?

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SUMMARY

The discussion clarifies the relationship between mass, potential energy, kinetic energy, and velocity in the context of gravitational motion. It establishes that while increasing mass results in higher potential energy (PE = mgh), it does not affect the velocity of an object in free fall when air resistance is negligible. The total energy (TE = PE + KE) remains constant throughout the fall, demonstrating that velocity is independent of mass, as shown by the equation KE = 1/2 mv². Thus, both a bowling ball and a tennis ball fall at the same rate of 9.8 m/s under gravity.

PREREQUISITES
  • Understanding of gravitational potential energy (PE = mgh)
  • Knowledge of kinetic energy (KE = 1/2 mv²)
  • Familiarity with the concept of total mechanical energy (TE = PE + KE)
  • Basic principles of physics regarding free fall and acceleration due to gravity
NEXT STEPS
  • Explore the implications of conservation of energy in mechanical systems
  • Study the effects of air resistance on falling objects
  • Investigate the relationship between mass and acceleration in different gravitational fields
  • Learn about the principles of projectile motion and its energy dynamics
USEFUL FOR

Students of physics, educators explaining gravitational concepts, and anyone interested in understanding the dynamics of motion and energy conservation in free-falling objects.

aatari
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Homework Statement


Hi Guys, I don't have a particular problem that I need to solve but I need help with understanding a concept. So we agree that irrespective of mass of an object they will both fall at a same rate if there is no air resistance. However, why is it then when we increase the mass of an object, the potential energy increases, which as a result increases the kinetic energy and which would also increase the velocity of that object.

Isn't this contradictory? Or am I misunderstanding something? Please help!

Homework Equations


Eg = mgh
Ek = 1/2mv^2

The Attempt at a Solution

 
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aatari said:
why is it then when we increase the mass of an object, the potential energy increases, which as a result increases the kinetic energy and which would also increase the velocity of that object.
That is false. Kinetic energy is not velocity. It depends on both mass and velocity. Different mass, different KE for the same velocity.
 
For an object dropped from rest from a specific height, y = h, the total energy at h, is TE = PE + KE. At y = h, PE = mgh and KE = 0 (rest). So TE = mgh.

The value of TE calculated does not change as the object falls. At any y value along the path, the total energy is the same, this includes the point at y=0. So, at y = 0, TE = PE + KE --> mg0 + 1/2 mv2 = TE = mgh. The mass cancels out which makes the velocity independent of the mass.
 
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in a simple way...try imagining a bowling ball falling from 1m on your hand vs a tennis ball falling they're pulled at the same speed 9.8m/s just the mass differs the impact on your hand) that velocity is the same just if maybe your friend pushes it down while dropping it it increases the speed..
 
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