NTA Abhyas JEE Main2020PhysicsMotion in Two DimensionsPractice
The trajectory of a projectile in vertical plane in y = a x - b x 2 , where a and b are constant and x and y are respectively horizontal and vertical distances of the projectile from the point of projection. The maximum height attained by the particle and the angle of projection from the horizontal is:
Options
- Aa 2 4 b , tan - 1 ( b )
- Ba 2 b , tan - 1 ( 2 b )
- Ca 2 4 b , tan - 1 ( a )
- D2 a 2 b , tan - 1 ( a )
Correct answer
C. a 2 4 b , tan - 1 ( a )
Step-by-step solution
Let the angle of projection be θ y = ax - bx 2 To get maxima, dy dx = 0 dy dx = a - b . 2x = 0 ⇒ x = a 2b y max = a 2 2 b - ba 2 4 b 2 = a 2 4b Angle of projections can be obtained by slope dy dx at x = 0 ⇒ Slope at x = 0 is a ⇒ tan θ = a ⇒ θ = tan -1 a