Florida Class E Drivers License Practice Test

What is the force of impact when you triple your speed?

1. It decreases

2. It doubles

3. It increases by nine times

4. It triples

The correct answer is: It increases by nine times

When you triple your speed, the force of impact increases by nine times due to the physics principle related to the kinetic energy of moving objects. Kinetic energy is calculated using the formula \( KE = \frac{1}{2} mv^2 \), where \( m \) is mass and \( v \) is velocity. If you triple the velocity, you are effectively increasing your speed from \( v \) to \( 3v \). Substituting this into the kinetic energy formula gives: \[ KE = \frac{1}{2} m (3v)^2 = \frac{1}{2} m (9v^2) = 9 \left(\frac{1}{2} m v^2\right) \] This shows that the kinetic energy, which is directly related to the force of impact in a collision, increases by a factor of nine. Thus, if your speed increases, especially at such a significant rate as tripling, the amount of force exerted during an impact becomes substantially greater, highlighting the importance of speed management for safety while driving.