The velocity of the wave also increases, because molecules at higher temperatures have more energy.
The instantaneous velocity is at a given instant in time while the average is calculated over the time interval of the entire journey. The instantaneous velocity can be determined by finding the gradient of the displacement/time graph while average velocity is given by total distance covered divided by total time taken.
6. D
7. D
8. B
let me know if you need clarification
The top box is cell and I’ll look at the others
-- Bob covered a distance of (32m + 45m) = 77 meters.
-- His displacement is the straight-line distance and direction
from his starting point to his ending point.
The straight-line distance is
D = √(32² + 45²)
D = √(1,024 + 2,025)
D = √3,049 = 55.22 meters
The direction is the angle whose tangent is (32/45) south of east.
tan⁻¹(32/45) = tan⁻¹(0.7111...) = 35.42° south of east.