a car goes from rest to 30 m/s in 12 s with constant acceleration. how long does it take the car to go from…

a car goes from rest to 30 m/s in 12 s with constant acceleration. how long does it take the car to go from rest to 15 m/s with the same acceleration?\na 3.0 s\nb 12/√2 s\nc 6.0 s\nd 12√2 s\ne 24 s

a car goes from rest to 30 m/s in 12 s with constant acceleration. how long does it take the car to go from rest to 15 m/s with the same acceleration?\na 3.0 s\nb 12/√2 s\nc 6.0 s\nd 12√2 s\ne 24 s

Answer

Explanation:

Step1: Calculate the acceleration

Use the formula $a=\frac{v - v_0}{t}$, where $v_0 = 0$ (starts from rest), $v = 30\ m/s$ and $t = 12\ s$. So $a=\frac{30 - 0}{12}=\frac{30}{12}= 2.5\ m/s^{2}$.

Step2: Calculate the new time

Use the same formula $a=\frac{v - v_0}{t}$, now $v_0 = 0$, $v = 15\ m/s$ and $a = 2.5\ m/s^{2}$. Rearranging for $t$ gives $t=\frac{v - v_0}{a}=\frac{15 - 0}{2.5}=6\ s$.

Answer:

C. 6.0 s