H2 Physics Flashcards

What is the first law of thermodynamics?

Answer: ΔU = Q + W, where ΔU is change in internal energy, Q is heat added, and W is work done on the system

First law of thermodynamics: ΔU = Q + W. The change in internal energy equals heat added to the system plus work done on the system. It is the law of conservation of energy for thermodynamic systems.

What is the condition for stationary waves to form?

Answer: Two coherent waves of the same frequency and amplitude travelling in opposite directions

Stationary (standing) waves form when two waves of the same frequency, amplitude, and wavelength travel in opposite directions and superpose. They have fixed nodes and antinodes.

A proton is accelerated from rest through a potential difference of 500V. What kinetic energy does it gain? (e = 1.6×10⁻¹⁹ C)

Answer: 8×10⁻¹⁷ J

KE gained = qV = 1.6×10⁻¹⁹ × 500 = 8×10⁻¹⁷ J.

What is the difference between progressive and stationary waves?

Answer: Progressive waves transfer energy; stationary waves do not transfer energy in the direction of the wave

Progressive waves transfer energy from one point to another. Stationary waves have nodes and antinodes — energy is stored between nodes but not transferred in the direction of the wave.

What is the formula for gravitational field strength?

Answer: g = GM/r²

Gravitational field strength g = GM/r², where G is the gravitational constant, M is the mass of the body causing the field, and r is the distance from its centre.

What is meant by 'isotopes'?

Answer: Atoms of the same element with the same number of protons but different numbers of neutrons

Isotopes are atoms of the same element (same atomic number/protons) but with different numbers of neutrons, and therefore different mass numbers.