Q124 / 160 · TS EAMCET 2021 (04 Aug Shift 1) · Physics

A car driver is trying to jump across a path as shown in figure by driving horizontally off a cliff 'X' at the speed 10 m s-1. When he touches peak Z (ignore air resistance), what would be speed? (use g=10 m s-2)

Figure

  • Correct answer
    A
    30 m s-1
  • B
    40 m s-1
  • C
    15 m s-1
  • D
    50 m s-1

Solution

Use the concept of conservation of energy in that case the sum of initial kinetic energy and potential energy should be equal to the sum of final kinetic energy and potential energy, 

⇒mgh+12mv2=mgh'+12mv'2⇒v'2=2gh+v2-2gh'

here, h'=60 m, h=100 m and v=10 m s-1, 

⇒v'2=2×10×100+102-2×10×60⇒v'=30 m s-1

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

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