Explanation

To calculate the efficiency (η) of a Carnot heat engine, use the formula:

η = 1 − (Tₗ / Tₕ)

Where:  

- Tₗ = Lower temperature = 300 K  

- Tₕ = Higher temperature = 500 K

η = 1 − (300 / 500) = 1 − 0.6 = 0.4 = 40%

Explanation

To find the charge (Q), use the formula:

Q = I × t

Where:  

- I = Current = 2 A  

- t = Time = 5 s  

Q = 2 × 5 = 10 C

Explanation

According to Charles's Law, at constant pressure, the volume of a gas increases with temperature.

Explanation

Specific heat capacity is defined as the amount of heat energy needed to raise the temperature of 1 kilogram of a substance by 1 degree Celsius (or 1 Kelvin).

It’s measured in J/kg·°C or J/kg·K.

Explanation

To find acceleration (a), use Newton’s Second Law:

F = m × a

Given:  

F = 20 N  

m = 5 kg  

So,  

a = F / m = 20 / 5 = 4 m/s²

Explanation

Newton's First Law of Motion is also known as the Law of Inertia.

It states that:

> "An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced external force."

This law explains why seatbelts are necessary — they provide the external force to stop you when a car suddenly stops.

Explanation

To find average acceleration, use the formula:

a = (v - u) / t

Where:  

- v = final velocity = 60 km/h = 16.67 m/s  

- u = initial velocity = 0  

- t = time = 10 s

a = (16.67 - 0) / 10 = 1.67 m/s²

Explanation

To calculate kinetic energy, use the formula:

KE = (1/2) × m × v²

Where:  

- m = mass = 2 kg  

- v = velocity = 3 m/s  

KE = ½ × 2 × (3)²  

KE = 1 × 9 = 9 J

Explanation

To find the speed of a wave, use the formula:

Speed = Frequency × Wavelength  

v = f × λ

Given:  

- Frequency (f) = 100 Hz  

- Wavelength (λ) = 2 m

v = 100 × 2 = 200 m/s

Explanation