Question

✦✧✧ Question ✧✧✦ ➠ ᴅᴏɴᴛ sᴘᴀᴍ⚠️ The kinetic energy of an object of mass m, moving with a velocity of 5 m/s is 25 J. What will be its kinetic energy when its speed is doubled? it is given here doubled not tripled​

Answer 1

Given :

• The kinetic energy of an object of mass m, moving with a velocity of 5 m/s is 25 J.

To Find :

• Kinetic energy when its speed is doubled .

Solution :

Firstly we'll find the mass of object :

Using Formula :

$\longmapsto\tt\boxed{Kinetic\:Energy=\dfrac{1}{2}\:{mv}^{2}}$

Putting Values :

$\longmapsto\tt{25=\dfrac{1}{2}\times{m}\times{{(5)}^{2}}}$

$\longmapsto\tt{25=\dfrac{1}{2}\times{m}\times{25}}$

$\longmapsto\tt{25\times{2}=25\:m}$

$\longmapsto\tt{50=25\:m}$

$\longmapsto\tt{m=\cancel\dfrac{50}{25}}$

$\purple\longmapsto\:\large\underline{\boxed{\bf\blue{m}\pink{=}\red{2\:kg}}}$

Now ,

• If speed is doubled :

$\longmapsto\tt{Speed=2\times{5}=10\:m/s}$

Using Formula :

$\longmapsto\tt\boxed{Kinetic\:Energy=\dfrac{1}{2}\:{mv}^{2}}$

Putting Values :

$\longmapsto\tt{\dfrac{1}{2}\times{2}\times{{(10)}^{2}}}$

$\longmapsto\tt{\dfrac{1}{{\not{2}}}\times{{\not{2}}}\times{100}}$

$\longmapsto\tt\bf{K.E=100\:J}$

Answer 2

Given :-

The kinetic energy of an object of mass m, moving with a velocity of 5 m/s is 25 J.

To Find :-

What will be its kinetic energy when its speed is doubled? it is given here doubled not tripled​

Solution :-

We know that

KE = 1/2 mv²

25 = 1/2 × m × (5)²

25 = 1/2 × m × 25

25 = 12.5m

25/12.5 = m

250/125 = m

2 = m

When speed is doubled

New speed = 5 × 2

New Speed = 10 m/s

KE' = 1/2 × m × v'²

KE' = 1/2 × 2 × (10)²

KE' = 1 × 100

KE' = 100 J

Hence,

We can say that the kinetic energy isn't doubled