The first thing you should know for this case is that density is defined as the quotient between mass and volume.
d = m / v
We have two states:
State 1:
d1 = 1.20 g / l
v1 = 1.02 × 106 l
State 2:
v2 = 1.09 × 106 l
Since the mass remains constant, then:
m = d1 * v1
Then, the density in state two will be:
d2 = m / v2
Substituting the value of the mass we have:
d2 = (d1 * v1) / v2
Substituting the values:
d2 = ((1.20) * (1.02 * 10 ^ 6)) / (1.09 * 10 ^ 6) = 1.12 g / l
answer:
The density of the heated air in the balloon is 1.12 g / l
Assuming the object is on earth the objects weight would be equal to its mass multiplied by the gravitational field constant
mass=22kg
g=9.80665N/kg
weight=(22 kg) (9.80665 N/kg)=215.7463N
generally g is rounded to be 10 N/kg so for any question where it asks the weight given the mass just multiply by 10 and that should suffice. In this case the answer would be 220 N
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