At what speed is the roller coaster cart moving when the brakes are applied?

To determine the speed of the roller coaster cart when the brakes are applied, it's important to understand the principles of motion and how brakes affect the velocity of a moving object. When brakes are engaged, the rolling friction and mechanical intervention reduce the cart's speed until it comes to a stop. The actual speed at the moment brakes are applied depends on several factors, including the intensity of the brakes, the weight of the cart, and the initial speed of the cart.

The speed of 85 km/h suggests that it is likely a reasonable estimate based on typical velocities for roller coasters at the moment brakes are activated, where high speeds are common before deceleration.

Further connecting this to the other speed options, those larger than 85 km/h would imply a higher initial speed, potentially inconsistent with the average braking dynamics, while those lower indicate a speed that may not reflect the typical scenarios in high-speed rides. This logic reinforces the choice of 85 km/h as the speed when the brakes are applied, as it represents a plausible and common scenario in roller coaster operation.