Pressure is defined as force per unit area and its SI unit is the pascal, so this Class 9 sheet opens with the definition and the unit of pressure. The answers add that upthrust equals the weight of liquid displaced and that pressure equals h × ρ × g.
Key Takeaways
Pressure is force per unit area (Q1).
The SI unit of pressure is the pascal (Q2).
Q6 records P = h × ρ × g.
Section A: Multiple Choice Questions (1 Mark Each)
Choose the correct option for each question.
1.Pressure is defined as
(a) force per unit area(b) force per unit volume(c) area per unit force(d) mass per unit area
2.The SI unit of pressure is
(a) pascal(b) newton(c) joule(d) watt
3.As the depth of a liquid increases, the pressure exerted by the liquid
(a) increases(b) decreases(c) stays the same(d) becomes zero
4.Archimedes' principle states that the upthrust on a body is equal to
(a) the weight of the liquid displaced(b) the weight of the body(c) the volume of the body(d) the density of the body
5.A body floating in a liquid displaces a volume of liquid whose weight
(a) equals the weight of the body(b) is greater than the weight of the body(c) is less than the weight of the body(d) is always equal to its own volume
6.The pressure at a depth h in a liquid of density ρ is given by
(a) P = h × ρ × g(b) P = h × g ÷ ρ(c) P = ρ ÷ (h × g)(d) P = h ÷ (ρ × g)
Section B: Short Answer Type Questions (2 Marks Each)
Show all steps clearly.
7.Define pressure and write its SI unit.
8.Write the formula for pressure.
9.Why does pressure increase with depth in a liquid?
10.State Archimedes' principle.
11.Why does a steel ship float even though steel is denser than water?
12.What is upthrust (buoyant force)?
13.Why does an object feel lighter when immersed in a liquid?
14.What is the upthrust on a floating body equal to?
Section C: Numericals & Word Problems (3 Marks Each)
Apply the concepts to solve the problems. Show all working.
15.A force of 100 N acts on an area of 5 m². Using P = F ÷ A, find the pressure.
16.A force of 60 N acts on an area of 0.5 m². Using P = F ÷ A, find the pressure.
17.A pressure of 200 Pa acts on an area of 4 m². Using F = P × A, find the force.
18.Calculate the pressure at a depth of 2 m in water. Using P = h × ρ × g with ρ = 1000 kg/m³ and g = 10 m/s².
19.A block weighing 40 N displaces 15 N of water when fully immersed. Find the upthrust on the block.
20.A body of mass 5 kg floats in water. Using W = m × g with g = 10 m/s², find the upthrust on it.
Answer Key
1. a) force per unit area
2. a) pascal
3. a) increases
4. a) the weight of the liquid displaced
5. a) equals the weight of the body
6. a) P = h × ρ × g
7. Refer to solution guide.
8. Refer to solution guide.
9. Refer to solution guide.
10. Refer to solution guide.
11. Refer to solution guide.
12. Refer to solution guide.
13. Refer to solution guide.
14. Refer to solution guide.
15. Refer to solution guide.
16. Refer to solution guide.
17. Refer to solution guide.
18. Refer to solution guide.
19. Refer to solution guide.
20. Refer to solution guide.
End of Worksheet
People Also Ask
What is pressure?
Force per unit area, option (a) in this worksheet (Q1).
What is the SI unit of pressure?
The pascal, option (a) in this worksheet (Q2).
What does upthrust equal?
The weight of the liquid displaced, option (a) in this worksheet (Q4).
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