# If an object with a mass of 5 kg  changes speed from 5m/s to 10 m/s, by how much does its kinetic energy change?

Mar 25, 2018

The object has gained $375 \setminus \text{J}$ of kinetic energy.

#### Explanation:

The initial kinetic energy is:

${\text{KE}}_{1} = m {v}_{1}^{2}$

• $m$ is the mass of the object in kilograms

• ${v}_{1}$ is the initial velocity, which is $5 \setminus \text{m/s}$.

And so, we get,

"KE"_1=5 \ "kg"*(5 \ "m/s")^2

$= 5 \setminus {\text{kg"*25 \ "m"^2"/s}}^{2}$

$= 125 \setminus \text{J}$

The final kinetic energy is:

${\text{KE}}_{2} = m {v}_{2}^{2}$

• ${v}_{2}$ is the final velocity, which is $10 \setminus \text{m/s}$.

Again, we just plug in values into the equation, and we get,

"KE"_2=5 \ "kg"*(10 \ "m/s")^2

$= 5 \setminus {\text{kg"*100 \ "m"^2"/s}}^{2}$

$= 500 \setminus \text{J}$

The change in kinetic energy is:

$\Delta {\text{KE"="KE"_2-"KE}}_{1}$

$= 500 \setminus \text{J"-125 \ "J}$

$= 375 \setminus \text{J}$