A particle is projected from level ground its kineitc energy K changes due to gravity so that `K_("max")//K_("min")=9`. The ratio of the range to the maxir, un height attained during its fight is
A. `sqrt(2)`
B. `4sqrt(2)`
C. 1.5
D. none

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1 Answers

`KE_("max")=(1)/(2)mv^(2)` (at the point of projection).
`KE_("min")=(1)/(2) mv^(2)cos ^(2)theta`
`(v^(2))/(v^(2)cos^(2)theta)=9 rArr cos theta=(1)/(3)`
as `R=(v^(2)sin2 theta)/(g), H=(v^(2)sin^(2) theta)/(2g)`
`R//H=4 cot theta`

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