Question

question 6 of 20 which change to an object would reduce its kinetic energy by half? a. reducing its mass to one - quarter of its original value b. reducing its mass to one - half of its original value c. increasing its velocity to four times its original value d. increasing its velocity to twice its original value

Explanation:

Step1: Recall kinetic - energy formula

The kinetic - energy formula is $K = \frac{1}{2}mv^{2}$, where $m$ is the mass and $v$ is the velocity.

Step2: Analyze option A

If $m$ becomes $\frac{1}{4}m$, then $K'=\frac{1}{2}(\frac{1}{4}m)v^{2}=\frac{1}{4}(\frac{1}{2}mv^{2})=\frac{1}{4}K$.

Step3: Analyze option B

If $m$ becomes $\frac{1}{2}m$, then $K'=\frac{1}{2}(\frac{1}{2}m)v^{2}=\frac{1}{2}(\frac{1}{2}mv^{2})=\frac{1}{2}K$.

Step4: Analyze option C

If $v$ becomes $4v$, then $K'=\frac{1}{2}m(4v)^{2}=\frac{1}{2}m\times16v^{2}=16K$.

Step5: Analyze option D

If $v$ becomes $2v$, then $K'=\frac{1}{2}m(2v)^{2}=\frac{1}{2}m\times4v^{2}=4K$.

Answer:

B. Reducing its mass to one - half of its original value