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प्रश्न
Calculate the decrease in the kinetic energy of a moving body if its velocity reduces to half of the initial velocity.
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उत्तर
We know for kinetic energy, body must have velocity
Let initial velocity = v
Also, Kinetic energy is equal to
K.E. = `1/2"m""v"^2`
given velocity decreased to half, so new velocity v'
v' = `"v"/2`
= K.Enew = `1/2 "m" xx ("v"/2)2`
= K.Enew = `1/2 "m" "v"^2/4`
∴ K.Enew = `("m""v"^2)/8`
Now, as asked, we need to find the decrease
Δ K.E = `("m""v"^2)/2 - ("m""v"^2)/8`
Δ K.E = `3/4"m""v"^2`
Kinetic energy will decrease by `3/4`th of initial kinetic energy.
संबंधित प्रश्न
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(b) What would have been the work done if he uses a lift in climbing the same vertical height?
Name the form of energy which a body may possess even when it is not in motion. Give an example to support your answer.
State the work energy theorem.
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State two advantages of using nuclear energy for producing electricity.
Name the energy changes for the following
human body
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Obtain an expression for the potential energy of a body of mass m at a height h above the ground.
Give one example when:
Potential energy changes to electric energy.
A body of mass 50 kg has a momentum of 3000 kg−1 ms. Calculate:
(j) the kinetic energy of the body.
(ii) the velocity of the body.
