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A rocket is moving up with a velocity up...

A rocket is moving up with a velocity `upsilon` if the velocity of this rocket is suddenly tripled, what will be the ratio of two kinetic energies ?

Text Solution

Verified by Experts

`Initial KE = (1)/(2) mu^2`
`"Final" KE = (1)/(2)m upsilon^(2) = (1)/(2)m (3u)^2 = (9)/(2)mu^2 (as upsilon - 3u)`
Thus, `("initial" KE)/("final"KE) = (1/2"mu"^(2))/(1/9"mu"^(2))=1/9=1:9`.
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Knowledge Check

  • The de Broglie wavelength of an electron moving with a velocity c/2 (c=velocity of light in vacuum) is equal to the wavelength of a photon. The ratio of the kinetic energies of electron and photon is

    A
    `1:4`
    B
    `1:2`
    C
    `1:1`
    D
    `2:1`

  • A photon and an electron moving with a velocity v have the same de broglie wavelength . Then the ratio of the kinetic energy of the electron to the kinetic energy of the photon is [C is the speed of light ]

    A
    a) `v/C`
    B
    b) `(2v)/(C )`
    C
    c) `(C )/(2v)`
    D
    d) `(v)/(2C)`

  • A body is thrown vertically up with certain initial velocity, the potential and kinetic energies of the body are equal is thrown with double the velocity upwards, the ratio of potential and kinetic energies upwards, the ratio of potential and kinetic energies of the body when it crosses the same point, is

    A
    `1 : 1`
    B
    `1 : 4`
    C
    `1 : 7`
    D
    `1 : 8`