Question

• always use significant figure rules. remember that these rules apply to all numbers that are measurements.
• in working this problem, assume the value of \g\ to be 9.8 m/s² with two (2) significant digits unless otherwise stated.

how many times does the kinetic energy of a car increase when traveling 60 mph as opposed to traveling 30 mph?
k.e. increases ______ times.
○ 4
○ 1/2
○ 2
○ 1/4

Explanation:

Step1: Escribir la fórmula de energía cinética

La energía cinética \( K.E.=\frac{1}{2}mv^{2} \), donde \( m \) es la masa y \( v \) es la velocidad.

Step2: Calcular la energía cinética para \( v_1 = 30\ mph \)

\( K.E._1=\frac{1}{2}m(30)^{2}=450m \)

Step3: Calcular la energía cinética para \( v_2 = 60\ mph \)

\( K.E._2=\frac{1}{2}m(60)^{2}=1800m \)

Step4: Encontrar la relación \( \frac{K.E._2}{K.E._1} \)

\( \frac{K.E._2}{K.E._1}=\frac{1800m}{450m}=4 \)

Answer:

A. 4