NEETPhysicsMotion in Two Dimensions
Two balls A and B are projected from the same position with horizontal velocity 20 m s - 1 and 5 m s - 1 as shown. The separation between these two bodies at the moment their velocities become perpendicular to each other is x m . The value of x is
Options
- A20
- B25
- C10
- D15
Correct answer
B. 25
Step-by-step solution
v 1 → = 5 i ^ - g t j ^ ⇒ u 1 = 5 v 2 → = 20 i ^ - g t j ^ ⇒ u 2 = 20 As v 1 → and v 2 → are perpendicular, v → 1 · v → 2 = 0 t = u 1 u 2 g s → rel = u → rel × t = ( u 1 + u 2 ) t = u 1 + u 2 u 1 u 2 g = 25 × 10 10 = 25 m