Jess wants to make her house more energy efficient. She has two options, A or B. Option A is double-glazing her patio doors, which will cost £350 and save £15 per year. Option B is insulating her loft, which will cost £460 and save £25 per year. Is option A or option B the better long-term option?

Distinguish between a transverse wave and a longitudinal wave.

The graph describes the motion of an object. the object moves with from a to b. it from b to c. it moves with from c to d.

Consider a 1000 w iron whose base plate is made of 0.5 cm thick aluminum alloy 2024-t6 (ρ = 2770 kg/m3 and cp = 875 j/kg°c). the base plate has a surface area of 0.03 m2. initially, the iron is in thermal equilibrium with the ambient air at 22°c. assuming 90% of the heat generated in the resistance wires is transferred to the plate, determine the minimum time needed for the plate temperature to reach 200°c.