Collision Impacts

📌 CONCEPT: In an inelastic collision, the force exerted on an object is equal to the rate of change of its momentum, which can be calculated using the formula F = Δp / Δt.

📐 RULE / FORMULA: F = Δp / Δt, where F is the force exerted on the object, Δp is the change in momentum, and Δt is the time over which the collision occurs.

💡 WORKED EXAMPLE: In this scenario, the car collides with the truck. The initial momentum of the car is its mass times its velocity (p_initial = 1500 kg * 25 m/s = 37500 kg m/s). The final momentum is zero since the car comes to rest after the collision. The change in momentum is Δp = p_final - p_initial = 0 - 37500 kg m/s = -37500 kg m/s. Assuming the collision time is Δt = 0.1 s, the force exerted on the car is F = Δp / Δt = -37500 kg m/s / 0.1 s = -375000 N.

⚠️ COMMON MISTAKE: Failing to consider the direction of the force, which is opposite to the direction of the change in momentum.