A car traveling at 30 m/s screeches to a halt, leaving 55-m-long skid marks. What was the car's acceleration while braking?

A care package is dropped out of a cargo plane and lands in the forest. If we assume the care package speed on impact is 54 m/s (123 mph), then what is its acceleration? Assume the trees and snow stops it over a distance of 3.0 m.

At the scene of a car accident, the forensic investigator measured the skid marks from one of the vehicles to be 83 m long. He also knows the typical acceleration for a car when you slam on the brakes is -4 m/s2. The speed limit for this area is 100 km/hr (about 28 m/s). Was the car speeding before it hit the brakes?

A rock is thrown from a bridge 18 m above water with an initial speed of 15.5 m/s. Assuming negligible air resistance, what is the speed that the rock hits the water with, in meters per second?