Q22 / 92 · NTA Abhyas (JEE Main) 2020 · Physics · Work Power Energy

A body is projected at an angle of 60° with the horizontal. If its kinetic energy at its maximum height is 10 J, then the height at which its potential energy and kinetic energy have equal values is (consider potential energy at the point of projection to be zero)

  • A
    half of the maximum height
  • Correct answer
    B
    two third of the maximum height
  • C
    one sixth of the maximum height
  • D
    insufficient data to solve the problem

Solution

KE at maximum height

1 2 mu 2 cos 2 6 0 ∘ = 1 0 J

1 2 mu 2 = 4 0 J

Mg H max = 3 0 J      ...(i)

When PE = KE

⇒    mgh = 2 0 =           ...(ii)

from (i) and (ii)

h H max = 2 3

Hence, the correct answer is option: 'B'.

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