Which factor primarily determines the impact force when colliding with a stationary object?

• A. Tire tread depth
• B. Speed of the vehicle
• C. Vehicle color
• D. Airbag status

Answer: (B)

Speed of the vehicle is the main driver of how hard a collision feels because the energy and momentum that must be stopped are set by how fast you’re going. The kinetic energy a car carries grows with the square of speed (1/2 m v^2), and momentum grows with speed (m v). When you hit a stationary object, that energy and momentum have to be dissipated in a short deceleration, so higher speed means a much larger force on impact unless the stopping distance or time increases to spread out that force. Features like airbags can help by making the stopping time/distance longer and distributing the load to occupants, reducing injury, but they don’t determine the initial impact energy that comes from speed. Tire tread depth affects braking and control before impact, not the immediate crash force once contact occurs, and vehicle color has no effect on the physics of the collision.