PHYSICS

JAMB 2012 - Question 18

Physics 2012 JAMB Past Questions - Question 18: A baloon whose volume is 300m³ is filled with hydrogen .If the density of air is 1.3kgm-³, find the up thrust on the balloon

Choose the correct answers from the options given.
A baloon whose volume is 300m³ is filled with hydrogen .If the density of air is 1.3kgm-³, find the up thrust on the balloon
A:
B:
C:
D:
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Correct Answer

C

Explanation

Mass of air displaced, m = density x volume= 1.3 x 300 = 390kg.upthrust = weight of air displaced= mg= 390x10 = 3900N
To find the upthrust on the balloon, we need to compare the weight of the displaced air with the weight of the balloon.

First, let's calculate the weight of the displaced air. The volume of the balloon is given as 300 m³, and the density of air is 1.3 kg/m³. Therefore, the mass of the displaced air is:

Mass = Density * Volume
      = 1.3 kg/m³ * 300 m³
      = 390 kg

Now, let's calculate the weight of the balloon. The weight of an object is given by the formula:

Weight = Mass * Gravity

Assuming the acceleration due to gravity is approximately 9.8 m/s², we can calculate the weight of the balloon:

Weight = Mass * Gravity
      = 390 kg * 9.8 m/s²
      = 3822 N

Therefore, the upthrust on the balloon is equal to the weight of the displaced air, which is 3822 N.