NEET2026PhysicsChapterActual
A drone starts from rest and accelerates vertically upward at 3 m s ⁻² . At t = 4 s , a small bolt detaches from the drone. What is the speed and magnitude of acceleration of the bolt at t = 7 s ? (Take g = 10 m s ⁻² )
Options
- A30 m s ⁻¹, 10 m s ⁻²
- B18 m s ⁻¹, 10 m s ⁻²
- C42 m s ⁻¹, 7 m s ⁻²
- D18 m s ⁻¹, 7 m s ⁻²
Correct answer
B. 18 m s ⁻¹, 10 m s ⁻²
Step-by-step solution
Velocity of the drone at t = 4 s is given by v = u + at . v = 0 + 3 4 = 12 m s ⁻¹ When the bolt detaches, it acquires the velocity of the drone at that instant. Thus, the initial velocity of the bolt is u_ b = 12 m s ⁻¹ (upward). After detaching, the bolt falls freely under gravity. Its acceleration is g = 10 m s ⁻² (downward). The time elapsed from detachment to t = 7 s is t = 7 - 4 = 3 s . Velocity of the bolt at t = 7 s is v_ b = u_ b - g t . v_ b = 12 - 10 3 = -18 m s ⁻¹ The negative sign indicates downward dir