Question

Which has more kinetic energy: a 0.0014-kg bullet traveling at 408 m/s or a 5.9 107-kg ocean liner traveling at 12 m/s (23 knots)? the bullet has greater kinetic energy the ocean liner has greater kinetic energy Justify your answer.Ek-bullet = JEk-ocean liner = J

Answer 1

Answer

The ocean liner has greater kinetic energy.

Energy bullet = 116.5248 J

Energy ocean liner = 4248000000 J

Explanation:

The kinetic energy of an object can be calculated as:

$E_k=\frac{1}{2}mv^2$

Where m is the mass and v is the velocity.

Then, replacing m = 0.0014 kg and v = 408 m/s we get that the kinetic energy of the bullet is:

$\begin{gathered} E_{k-\text{bullet}}=\frac{1}{2}(0.0014)(408)^2 \\ E_{k-\text{bullet}}=\frac{1}{2}(0.0014)(166464) \\ E_{k-\text{bullet}}=116.5248\text{ J} \end{gathered}$

In the same way, we can replace m = 5.9 x 10^7 kg and v = 12 m/s to find the kinetic energy of the ocean liner as:

$\begin{gathered} E_{k-ocean\text{ liner}}=\frac{1}{2}(5.9\times10^7)(12)^2 \\ _{}E_{k-ocean\text{ liner}}=\frac{1}{2}(5.9\times10^7)(144) \\ E_{k-ocean\text{ liner}}=4248000000\text{ J} \end{gathered}$

Therefore, the ocean liner has greater kinetic energy.

So, the answers are:

The ocean liner has greater kinetic energy.

Energy bullet = 116.5248 J

Energy ocean liner = 4248000000 J