Calculating Acceleration of Rising Balloon

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SUMMARY

The acceleration of a rising hot-air balloon, given the air density ratio of 1.30, is not simply 1.3 times the acceleration due to gravity (g = 9.81 m/s²). The correct approach involves understanding buoyancy and the net force acting on the balloon. The effective acceleration can be derived from the difference in densities, leading to a calculation that results in an upward acceleration of approximately 3.77 m/s², factoring in the buoyant force acting against gravity.

PREREQUISITES
  • Understanding of buoyancy principles in fluid dynamics
  • Basic knowledge of Newton's second law of motion
  • Familiarity with the concept of density and its impact on forces
  • Ability to perform calculations involving ratios and gravitational acceleration
NEXT STEPS
  • Study the principles of buoyancy and Archimedes' principle
  • Learn how to apply Newton's second law to fluid dynamics scenarios
  • Explore the relationship between density and buoyant force
  • Practice solving problems involving varying densities and gravitational effects
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and fluid dynamics, as well as educators seeking to clarify concepts related to buoyancy and acceleration in gases.

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Homework Statement



What is the acceleration of a rising hot-air balloon if the ratio of the air density outside the balloon to that inside is 1.30? Neglect the mass of the balloon fabric and the basket.


Homework Equations


g=9.81 m/s^s

The Attempt at a Solution



I thought it would just be 1.3 times g=
1.3(9.81)=12.75 m/s

my homework says it is wrong...why?
 
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if the ratio was 1:1 the acceleration would be 9.81m/s^2 downwards. So how much lighter is the air in the balloon actually?
 

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