The Correct Answer and Explanation is:
The correct answer is: on the approach is too great.
Here is a detailed explanation:
This answer is rooted in the fundamental principles of physics that govern a moving vehicle. When a car travels through a curve, it must constantly change its direction. According to Newton’s first law of motion, an object in motion will stay in motion in a straight line unless acted upon by an external force. For a car in a turn, this external force is the centripetal force, which is generated by the friction between the tires and the road surface. This force pulls the car toward the center of the curve, allowing it to turn instead of continuing straight.
The amount of centripetal force required to keep a car in a turn is directly related to its speed. Specifically, the required force increases with the square of the vehicle’s velocity. This means that if you double your speed, you need four times the amount of frictional force from your tires to safely navigate the same curve.
The problem arises when the speed on the approach to the curve is too great. If a vehicle enters a turn too fast, the force required to make the turn may exceed the maximum available friction between the tires and the road. When this happens, the tires lose their grip, and the car begins to skid. Due to inertia, the car will tend to continue in a straight line, which often leads to it running off the road or into an opposing lane of traffic, resulting in a collision.
Therefore, the most critical moment for safety at a curve is the approach. A driver must accurately judge the sharpness of the curve ahead and reduce their speed to a safe level before they begin turning. Braking while already in the middle of a curve can further upset the vehicle’s balance and reduce the tires’ ability to provide the necessary sideways grip, making a loss of control even more likely. The initial entry speed dictates whether a safe passage is possible.
