We are asked to determine the force required to stop a car traveling at a speed of 28 m/s in 5.8s. To do that we will calculate the acceleration of the car first. The acceleration is determined using the following equation:
Where
Since we are calculating the force when the car stops this means that the final velocity is zero:
Now we solve for the acceleration "a", first by subtracting the initial velocity from both sides:
Now we divide by the time "t":
Now we substitute the values:
Solving the operations we get:
Now, we use Newton's second law to determine the force:
Where:
Substituting the value we get:
Solving the operations we get:
Therefore, the required force is -6148.59 Newtons. The negative sign means that the force is acting in the opposite direction of the movement of the car.