Page 63 - Physics Form 5 KSSM_Neat

Example 1 LET’S ANSWER CHAPTER 2
LET’S ANSWER
The blood pressure reading of a patient is 160/100. What is the Pressure
pressure 160 mm Hg in Pa?
[Density of Hg, ρ = 1.36 × 10 kg m and
4
–3
gravitational acceleration, g = 9.81 m s ]
–2
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Solution

Step 1: Step 2: Step 3: Step 4:
Identify the Identify the Identify the formula Solve the problem
problem information given that can be used numerically

 Pressure 160 mm Hg in Pa 3 P = hρg

 Height of liquid column, h = 160 mm  P = 0.16 × 1.36 × 10 × 9.81
4
= 0.16 m = 2.13 × 10 Pa
4
Gravitational acceleration, g = 9.81 m s –2
Density of Hg, ρ = 1.36 × 10 kg m –3
4

Example 2

5
The maximum pressure that a wall at the seaside can withstand is 3.6 × 10 Pa. What is this
maximum pressure in m H O?
2
–3
3
–2
[Density of H O, ρ = 1.00 × 10 kg m and gravitational acceleration, g = 9.81 m s ]
2
Solution
Maximum pressure, P = 3.6 × 10 Pa
5
Density of H O, ρ = 1.00 × 10 kg m –3
3
2
Gravitational acceleration, g = 9.81 m s –2
P = hρg
P
h =
ρg
3.6 × 10 5
=
1.00 × 10 × 9.81
3
= 36.7 m
Maximum pressure = 36.7 m H O
2

LS 2.2.3 53