Which quantity best describes this description? justin walks at 3 miles per hour north, and then speeds up to 4 miles per hour.

(this is a question from ipc,)

i just wanted to check with

the answers are:

a. acceleration
b. velocity
c. inertia
d. speed

i went with acceleration, but it could also be velocity, since it's walking in a certain kind of direction.

i wanted to know if anyone else had thoughts, or if i should change my answer to b?

The difference between a red shift and a blue shift has to do with wavelength frequency. t or f

Asolid round steel rod 6.25 mm in diameter and 375 mm long is rigidly bonded to the end of solid square brass rod 25 mm on a side and 300 mm long. the geometric axes of the bare are along the same line. an axial tensile force of 5.4 kn is applied at the extreme ends of the assembly. for steel e = 200 gpa and for brass e = 90 gpa. determine the total elongation for the assembly.

Arefrigerator uses r-134a as the working fluid and operates on the ideal vapor-compression refrigeration cycle except for the compression process. the refrigerant enters the evaporator at 120 kpa with a quality of 34 percent and leaves the compressor at 70°c. if the compressor consumes 450 w of power, determine (a) the mass flow rate of the refrigerant, (b) the condenser pressure, and (c) the cop of the refrigerator. (0.00644 kg/s, 800 kpa, 2.03)