Final answer:
The magnitude of the net force required to stop a 1750kg car from a speed of 120km/h over a distance of 61 meters is 8970N, which corresponds to option D.
Step-by-step explanation:
To calculate the magnitude of the net force required to bring a 1750kg car to rest from a speed of 120km/h over a distance of 61m, we can use the work-energy principle. This principle states that the work done by the net force is equal to the change in kinetic energy of the car. The kinetic energy (KE) of the car can be calculated using the formula KE = 1/2 * m * v2, where m is the mass of the car, and v is the velocity of the car.
First, we need to convert the speed from km/h to m/s: 120 km/h = 120 * (1000 m / 3600 s) = 33.33 m/s. The initial kinetic energy (KEi) is then KEi = 1/2 * 1750 kg * (33.33 m/s)2. Since the car comes to rest, the final kinetic energy (KEf) is 0. The work done by the net force is equal to the change in kinetic energy, so we have Work = KEf - KEi = 0 - KEi.
The net force can be calculated using the work formula, Work = Force * distance. So, by rearranging the formula for force, we get Force = Work / distance. Substituting all the known values, we can solve for the magnitude of the force. Performing the calculations, we find that the force required to stop the car over a distance of 61 meters is 8970N, which is option D in the multiple-choice answers provided.