Question

Two bodies are projected from ground with equal speed $ 20\,m/s $ from the same position in the same vertical plane to have equal range but at different angles above the horizontal. If one of the angle is $30^{\circ}$ the sum of their maximum heights is (assume $ g=10\,m/s^{2} $ )

• A. $ 400\,\,m $
• B. $ 20\,\,m $
• C. $ 30\,\,m $
• D. $ 40\,\,m $

Answer 1

Answer: (D)

$ h_{ \max} = \frac{ u^2 }{ 2 g } $
$ \therefore h_{ \max} = \frac{ ( 20)^2 }{ 2 \times 10 } = 20 \, m $
For the second body also $ h_{ \max} = 20\, m $
$ \therefore $ Sum of maximum heights $= 20\, m + 20\, m $
$= 40 \,m$