Let's solve the problem step-by-step:
1. Calculate the initial kinetic energy (KE_initial):
[tex]\[
KE_{\text{initial}} = \frac{1}{2} m v_\text{initial}^2
\][/tex]
- Mass ([tex]\(m\)[/tex]) of the puppy: 3 kilograms
- Initial speed ([tex]\(v_{\text{initial}}\)[/tex]): 2 meters/second
Substituting the values:
[tex]\[
KE_{\text{initial}} = \frac{1}{2} \times 3 \times (2)^2
\][/tex]
[tex]\[
KE_{\text{initial}} = \frac{1}{2} \times 3 \times 4
\][/tex]
[tex]\[
KE_{\text{initial}} = 6 \, J
\][/tex]
2. Calculate the final kinetic energy (KE_final):
[tex]\[
KE_{\text{final}} = \frac{1}{2} m v_\text{final}^2
\][/tex]
- Final speed ([tex]\(v_{\text{final}}\)[/tex]): 1 meter/second
Substituting the values:
[tex]\[
KE_{\text{final}} = \frac{1}{2} \times 3 \times (1)^2
\][/tex]
[tex]\[
KE_{\text{final}} = \frac{1}{2} \times 3 \times 1
\][/tex]
[tex]\[
KE_{\text{final}} = 1.5 \, J
\][/tex]
3. Calculate the decrease in kinetic energy:
[tex]\[
\text{Decrease in KE} = KE_{\text{initial}} - KE_{\text{final}}
\][/tex]
Substituting the calculated values:
[tex]\[
\text{Decrease in KE} = 6 \, J - 1.5 \, J
\][/tex]
[tex]\[
\text{Decrease in KE} = 4.5 \, J
\][/tex]
From this, we see that her kinetic energy decreases, and the final kinetic energy is [tex]\(1.5 \, J\)[/tex]. Therefore, the correct answer is:
A. Her kinetic energy decreases to [tex]\(1.5 \, J\)[/tex].
