Q. A particle has initial velocity (3î + 4ĵ) and has acceleration (0.4î + 0.3ĵ). Its speed after 10 s is
A) 10 units
B) 7 units
C) 7√2 units
D) 8.5 units
Explanation
[Solution from source] v = u + at = (3 + 0.4×10)î + (4 + 0.3×10)ĵ = 7î + 7ĵ. Speed = √(49 + 49) = 7√2 ≈ 9.9 units. Adding the initial speed 5 and the gain 5 to get 10 units wrongly adds magnitudes of non-parallel vectors. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.