a) One similarity between heat and temperature is that both are related to the internal energy of a substance.

Here are the solutions to the questions: 5. a) One similarity between heat and temperature is that both are related to the internal energy of a substance. b) The linear expansivity of metal Y (_Y = 1.82 × 10^-5 K^-1) is greater than that of metal X (_X = 1.51 × 10^-5 K^-1). When heated, metal Y expands more than metal X. Therefore, the bimetallic strip will bend towards metal X (the metal with lower expansivity). Diagram of bimetallic strip after heating: ` Y / / / X ` (The strip bends with X on the inside of the curve and Y on the outside.) 6. i) Let L_P, L_Q, L_R be the lengths of strings P, Q, and R respectively. Given: L_P = 2 L_Q Given: L_R = (1)/(3) L_Q From the first equation, L_Q = (1)/(2) L_P. Substitute this into the second equation: L_R = (1)/(3) ((1)/(2) L_P) L_R = (1)/(6) L_P The relationship between P and R is L_P = 6 L_R. ii) The string that will produce a note of the highest pitch when plucked is R. iii) The reason is that the frequency of a vibrating string is inversely proportional to its length (for equal tension). String R is the shortest (L_R = (1)/(3) L_Q), so it will vibrate at the highest frequency, producing the highest pitch. 7. To determine the angle of refraction, we use Snell's Law: ( i)/( r) = (v_1)/(v_2) Step 1: Substitute the given values into the formula. ( 60^)/( r) = 3.0 × 10^8 ms^-12.0 × 10^8 ms^-1 ( 60^)/( r) = 1.5 Step 2: Solve for r. r = ( 60^)/(1.5) = (0.8660)/(1.5) r ≈ 0.5773 Step 3: Calculate the angle of refraction, r. r = (0.5773) r ≈ 35.26^ 8. a) Two uses of electromagnets are: • In electric bells • In lifting heavy iron objects (e.g., in scrap yards) b) The soft iron bar can be converted to a magnet by the stroking method. Stroke the soft iron bar repeatedly in the same direction with one pole of the bar magnet. This aligns the magnetic domains within the soft iron, magnetizing it. 9. a) Reactance is the opposition to the flow of alternating current (AC) in a circuit due to the presence of capacitance or inductance. It is measured in ohms (). b) To calculate the frequency, we use the formula for capacitive reactance: X_C = (1)/(2 f C) Step 1: Rearrange the formula to solve for frequency, f. f = (1)/(2 X_C C) Step 2: Substitute the given values (C = 5 µF = 5 × 10^-6 F, X_C = 3000 Ω, = 3.14). f = (1)/(2 × 3.14 × 3000 Ω) × 5 × 10^-6 F Step 3: Calculate the frequency. f = (1)/(0.0942) f ≈ 10.62 Hz 10. a) Photo-electrons are electrons emitted from the surface of a material (typically a metal) when light of a sufficiently high frequency shines on it, a phenomenon known as the photoelectric effect. b) To calculate the threshold frequency, we first convert the work function to Joules. Step 1: Convert the work function () from electron volts (eV) to Joules (J). = 3.5 eV × (1.6 × 10^-19 J/eV) = 5.6 × 10^-19 J Step 2: Use the formula relating work function and threshold frequency (f_0). = h f_0 Step 3: Solve for f_0 and substitute Planck's constant (h = 6.6 × 10^-34 Js). f_0 = ()/(h) = 5.6 × 10^-19 J6.6 × 10^-34 Js f_0 ≈ 8.48 × 10^14 Hz 11. a) Two health hazards of X-rays are: • Cell damage and increased risk of cancer. • Genetic mutations in reproductive cells. b) The distinction between soft and hard X-rays is primarily based on their energy and penetrating power: • Soft X-rays have lower energy, longer wavelengths, and are less penetrating. • Hard X-rays have higher energy, shorter wavelengths, and are more penetrating. 3 done, 2 left today. You're making progress.