Question

Kinetic energy of an object is 25 j. Velocity is 5 m/s what will be its kinetic energy if velocity is doubles?

Answer 1

`"100 J"`

Explanation:

`"KE"=(1/2)*m*v^2`

Simple explanation :

Since the KE is proportional to velocity squared, if you increase the KE by a factor of `2`, you increase `v` by a factor of `2^2= 4`

Detailed explanation :

`25=0.5*m*(5^2)`

Find `m`:

`25=25m/2`

`m=2`

Hence the new KE:

`"KE"=0.5*2*10^2`

`"KE"=100 J`

Answer 2

The kinetic energy of body is `"100 J"`.

Explanation:

`"kinetic energy" =1/2 xx mxxv^2="25 J"`

`v = "5 m/s"`

Let the mass of body be `m`.

`1/2xxmxxv^2=25`

`mxx5^2=50`

`mxx 25=50`

`m=50/25`

or

`m = "2 kg"`

Now if velocity is doubled then

`v'=2 * v`

`v'=2×x5`

`v' = "10 m/s"`

The final kinetic energy `=1/2xxmxx(v')^2`

`=1/2x×2x×10^2`

`=1/2x×2x×100`

`=100J`

Answer 3

`100J`

Explanation:

We know that the equation for kinetic energy is

`KE=1/2mv^2`

Here, `v=5`, `KE=25`

`:.25=1/2*m*5^2`

`25=1/2*25*m`

`:.m=2`

So, the object's mass is `2kg`.

If the velocity doubles, then `v=5*2=10`, and then

`KE=1/2*10^2*2`

`KE=100J`

So, the object's kinetic energy will be `100J`.