Physics Formula DSE

Understanding Physics Formulas in DSE

The Diploma of Secondary Education (DSE) in Physics covers various fundamental formulas that are essential for students to understand and apply. These formulas span different areas of physics, including mechanics, electricity, magnetism, waves, and thermodynamics. Below is a detailed explanation of some key formulas, along with examples.

1. Mechanics

Newton's Second Law of Motion

\[ F = ma \]

• F is the force in newtons (N)
• m is the mass in kilograms (kg)
• a is the acceleration in meters per second squared (m/s²)

Example:

If a 10 kg object is accelerating at 2 m/s², the force applied is:

\[ F = 10 \, \text{kg} \times 2 \, \text{m/s}^2 = 20 \, \text{N} \]

Kinetic Energy

\[ KE = \frac{1}{2}mv^2 \]

• KE is the kinetic energy in joules (J)
• m is the mass in kilograms (kg)
• v is the velocity in meters per second (m/s)

Example:

If an object of mass 5 kg is moving at a velocity of 3 m/s, its kinetic energy is:

\[ KE = \frac{1}{2} \times 5 \, \text{kg} \times (3 \, \text{m/s})^2 = 22.5 \, \text{J} \]

2. Electricity and Magnetism

Ohm's Law

\[ V = IR \]

• V is the voltage in volts (V)
• I is the current in amperes (A)
• R is the resistance in ohms (Ω)

Example:

If a circuit has a current of 2 A and a resistance of 5 Ω, the voltage is:

\[ V = 2 \, \text{A} \times 5 \, \text{Ω} = 10 \, \text{V} \]

Magnetic Force on a Current-Carrying Conductor

\[ F = BIL \sin \theta \]

• F is the force in newtons (N)
• B is the magnetic field strength in teslas (T)
• I is the current in amperes (A)
• L is the length of the conductor in meters (m)
• θ is the angle between the conductor and the magnetic field

Example:

If a conductor carrying a current of 3 A is placed in a magnetic field of 0.5 T at an angle of 90 degrees, and the conductor's length is 2 m, the force is:

\[ F = 0.5 \, \text{T} \times 3 \, \text{A} \times 2 \, \text{m} \times \sin 90^\circ = 3 \, \text{N} \]

3. Waves

Wave Equation

\[ v = f\lambda \]

• v is the wave velocity in meters per second (m/s)
• f is the frequency in hertz (Hz)
• \lambda is the wavelength in meters (m)

Example:

If a wave has a frequency of 50 Hz and a wavelength of 0.1 m, its velocity is:

\[ v = 50 \, \text{Hz} \times 0.1 \, \text{m} = 5 \, \text{m/s} \]

4. Thermodynamics

First Law of Thermodynamics

\[ \Delta U = Q - W \]

• \Delta U is the change in internal energy in joules (J)
• Q is the heat added to the system in joules (J)
• W is the work done by the system in joules (J)

Example:

If 500 J of heat is added to a system and it does 200 J of work, the change in internal energy is:

\[ \Delta U = 500 \, \text{J} - 200 \, \text{J} = 300 \, \text{J} \]

Conclusion

Understanding these fundamental physics formulas is crucial for success in the DSE. They provide the foundation for solving various problems in mechanics, electricity, magnetism, waves, and thermodynamics. Mastery of these concepts will enable students to excel in their physics examinations and practical applications.

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