Kinematics of motion phases to find v

Steps:

• Acceleration and deceleration times total 12 s - 8 s = 4 s; assume symmetry, so each 2 s.
• Acceleration distance: average speed (v/2) × 2 s = v m.
• Constant speed distance: v × 8 s = 8v m.
• Deceleration distance: v m.
• Total distance: v + 8v + v = 10v = 60 m → v = 6 m/s.

Why C is correct:

• v = 6 m/s satisfies the equation for total distance using uniform acceleration formula s = (u + v)t/2.

Why the others are wrong:

• A: Gives 10 × 3 = 30 m, less than 60 m.
• B: Gives 10 × 5 = 50 m, less than 60 m.
• D: Gives 10 × 15 = 150 m, more than 60 m.

Final answer: C