Explanation

For a nozzle: steady flow energy equation, adiabatic, no work, PE negligible.

h₁ + KE₁ = h₂ + KE₂  

Given:  

h₁ = 300 kJ/kg, h₂ = 260 kJ/kg, KE₁ ≈ 0 because inlet velocity is negligible  

KE₂ = h₁ - h₂  

KE₂ = 300 - 260 = 40 kJ/kg

Last verified on 26-06-2026

Explanation

Polytropic: P V^n = C, here n = 2.0  

So P₁ V₁² = P₂ V₂²  

Given: P₁ = 1000 kPa, V₁ = 1 m³, V₂ = 2 m³  

P₂ = P₁ × V₁² / V₂²  

P₂ = 1000 × 1² / 2²  

P₂ = 1000 / 4 = 250 kPa

Volume doubles → pressure drops to 1/4.  

250 kPa is below 300 kPa, so pressure decreases below 300 kPa.

Last verified on 26-06-2026

Explanation

For ideal gas: Density d = PM / RT  

Given:  

P = 8.21 atm, M = 28 g/mol, T = 280 K, R = 0.0821 L·atm/mol·K  

d = (8.21 × 28) / (0.0821 × 280)  

d = 229.88 / 22.988  

d ≈ 10 g/L

Last verified on 26-06-2026

Explanation

Formula: K = °C + 273.15  

So 25°C = 25 + 273.15 = 298.15 K.

Last verified on 26-06-2026

Explanation

Volume is constant → use Gay-Lussac's Law: P₁/T₁ = P₂/T₂  

Given:  

P₁ = 1.5 atm, T₁ = 300 K, T₂ = 600 K  

P₂ = P₁ × T₂ / T₁  

P₂ = 1.5 × 600 / 300  

P₂ = 900 / 300 = 3.0 atm

Temp doubled from 300 K to 600 K, so pressure also doubles from 1.5 atm to 3.0 atm.

Last verified on 26-06-2026

Explanation

Pressure is constant → use Charles's Law: V₁/T₁ = V₂/T₂  

Given:  

V₁ = 3.0 L, T₁ = 300 K, T₂ = 450 K  

V₂ = V₁ × T₂ / T₁  

V₂ = 3.0 × 450 / 300  

V₂ = 1350 / 300 = 4.5 L

So when temp goes from 300 K to 450 K, volume increases from 3.0 L to 4.5 L.

Last verified on 26-06-2026

Explanation

• Electric current is the flow of electric charge.
• In metals, this charge is mainly carried by electrons.
• Current is measured in amperes (A).
• Without charge movement, there is no electric current.

Last verified on 25-06-2026

Explanation

• CFCs, carbon dioxide (CO₂), and methane (CH₄) are all greenhouse gases.
• Carbon dioxide traps heat in the atmosphere and increases temperature.
• Methane is a very strong greenhouse gas with high warming effect.
• CFCs also damage the ozone layer and act as greenhouse gases.

Last verified on 16-06-2026

Explanation

• White clothes are worn in hot climate because they reflect most of the sunlight and absorb very little heat.
• This helps keep the body cool in high temperatures.
• Dark colors like black absorb more heat, making the body warmer.

Last verified on 25-06-2026

Explanation

• A rectifier is an electrical device that converts Alternating Current (AC) into Direct Current (DC).
• It allows current to flow in only one direction.
• It is commonly used in power supplies and chargers.
• Rectifiers use components like diodes for conversion.

Last verified on 25-06-2026