Question

6 the kinetic energy e of a moving object is given by $e = \frac{1}{2}mv^{2}$, where m is its mass in kilograms and v is its speed in meters/second.
6a if a vehicle traveling at 20 m/s has kinetic energy $e = 500000$, what is the mass of the car?
2500
$m = 2500$
5 great job!
6b if a vehicle is traveling at 20 m/s, what is its speed in kilometers/hour to one decimal place?
$20 m/s=$ km/h

Explanation:

Step1: Convert meters to kilometers

Since \(1\) kilometer \( = 1000\) meters, so \(1\) meter \(=\frac{1}{1000}\) kilometers.

Step2: Convert seconds to hours

Since \(1\) hour \( = 3600\) seconds, so \(1\) second \(=\frac{1}{3600}\) hours.

Step3: Use the conversion formula

We know that \(1\ m/s=\frac{\frac{1}{1000}\ km}{\frac{1}{3600}\ h}=\frac{3600}{1000}\ km/h = 3.6\ km/h\).
For a speed of \(v = 20\ m/s\), then \(v=20\times3.6\ km/h\).

Answer:

\(72.0\)