Question

imagine you are driving a car down the road next to a large 18 - wheel semi - truck. both of you are traveling at the same speed, and traffic in front of you stops suddenly. which natural law of driving explains why you will be able to stop before the semi - truck can? a doppler effect b centrifugal force c kinetic energy d momentum

Explanation:

• Doppler effect: It is related to the change in frequency of waves (like sound or light) due to the relative motion of the source and the observer. It has nothing to do with stopping a vehicle.
• Centrifugal force: It is a pseudo - force experienced in a rotating frame of reference. It is not relevant to the linear motion of stopping a car or a truck on a straight road (assuming the stop is in a straight - line motion scenario).
• Kinetic energy: The formula for kinetic energy is \(K = \frac{1}{2}mv^{2}\). While kinetic energy is related to the motion of an object, when we talk about stopping a vehicle, the key concept related to the "effort" (force and distance) to stop is momentum.
• Momentum: The formula for momentum is \(p=mv\). Since the truck has a much larger mass \(m\) than the car and they are moving at the same speed \(v\), the truck has a larger momentum. According to the impulse - momentum theorem \(F\Delta t=\Delta p\). If we assume similar braking forces \(F\) (in a very rough sense, as braking systems can be different, but for the sake of the concept), a larger \(\Delta p\) (change in momentum, here from \(mv\) to \(0\)) for the truck means it will take more time and distance to stop.

Answer:

D. momentum