Question

An object with a mass of 40 kg is moving with a velocity of 10 10m/s . Find its kinetic energy .

Answer 1

Answer:

Given , Mass of object  ,m=10 kg

Velocity of object , v=20ms−1

Initial Kinetic energy , K1=21×10×202=2000 J

Now Final mass  ,m2=20 kg

Final Velocity , v2=10m/s

Final Kinetic energy , K2=21×20×102=1000 J

Required Ratio=K2K1=10002000=2

Explanation:

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Answer 2

$\huge {\blue {\underline{\green {\underline {\green{\bf{Answer : }}}}}}}$

${\red{\bf{Given : }}}$

Mass of the object, m = 450 Kg

Velocity of the object, v = 15m/s

${\purple{\bf{To\: find : }}}$

Kinetic Energy of the object

${\orange{\bf{Solution : }}}$

Kinetic energy is directly proportional to the mass of the object and to the square of its velocity. It is scalar quantity .i.e.,

${ \leadsto{ \bf{K.E = \dfrac{1}{2}mv^2}}}$

Here ,

• KE = Kinetic energy
• M = mass
• V = Velocity

so, Substituting all the given values in the formula

${ \leadsto{ \bf{K.E = \dfrac{1}{2} \times 40 \times{10}^{2} }}}$

${\leadsto{\bf{ KE = 20 × 100}}}$

${\leadsto{ \boxed{\bf{ KE = 2000 J}}}}$

Thus,the kinetic energy of the object is 2000J.

Remember !

SI unit of kinetic energy is Joules