Page 56 - Physics Form 5 KSSM_Neat

Solution

(a) 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
KEMENTERIAN PENDIDIKAN MALAYSIA
 Pressure on the fish, P  P = hρg

 Depth of the fish, h = 1.5 m  P = hρg
Density of aquarium water, ρ = 1 050 kg m = 1.5 × 1 050 × 9.81
–3
Gravitational acceleration, g = 9.81 m s –2 = 15 450.8 Pa
= 15.5 kPa

(b) Atmospheric pressure, P atm = 100 kPa
Actual pressure = hρg + P atm
= 15.5 + 100
= 115.5 kPa

Example 2

Figure 2.8 shows a U-tube filled with water and olive oil.
The density of water is 1 000 kg m . Calculate the density
–3
of olive oil.
Water
16.5 cm
Solution 15.0 cm
Density of olive oil, ρ 2
Height of water column, h = 15.0 cm Olive oil
1
Density of water, ρ = 1 000 kg m –3
1
Height of olive oil column, h = 16.5 cm
2 Figure 2.8
h ρ g = h ρ g
2 2
1 1
h ρ = h ρ
1 1
2 2
15.0 × 1 000 = 16.5 × ρ 2
15.0 × 1 000
ρ =
2 16.5
= 909.1 kg m –3

46 LS 2.1.3