Question 18
Density and UpthrustA balloon whose volume is 300m3 is filled with hydrogen. If the density of air is 1.3 kgm−3, find the upthrust on the balloon. [g ≈ 10ms−2]
- A.3000N
- B.3800N
- C.3900N
- D.4200N.
Show the answer and explanation
Answer: C (3900N)
Explanation
Upthrust = weight of air displaced = Vρg = 300 × 1.3 × 10 = 3900 N.