Acar braked with a constant deceleration of 8 ft/s2, producing skid marks measuring 100 ft before coming to a stop. how fast was the car traveling when the brakes were first applied?

In physics, it is convenient that there are already derived formulas for rectilinear motion at constant acceleration from Newton's Law of motion. One of these equations useful for this problem is:

2ax = vf2 - v02, where a is the acceleration, x is the distance, vf is the final velocity and v0 is the initial velocity.

Now, a=-8 ft/s2. It is negative because the car is decelerating. The distance x is 100 ft, the vf is equal to 0m/s because the car comes to a stop. The only unknown would be v0.

2(-8 ft/s2)(100 ft) = (0m/s)^2 - v0^2
v0 = 40 m/s

The objects do not reach terminal velocity         there is not enough time from the time the object falls from when it hits the ground to achieve terminal velocity. an object must be placed higher to achieve terminal velocity in order to be in free fall.