An object starts from rest and accelerates uniformly at 6 m/s² for 7 s. What is its final speed?

A) 21 m/s

B) 42 m/s

C) 63 m/s

D) 84 m/s

Answer: B

Explanation: Use final speed = acceleration × time from rest for the stated idealized conditions. Substitution gives 6 × 7 = 42 m/s.