An automobile of mass 2000 kg is driven into a brick wall in a safety test. the bumper behaves like a hooke’s-law spring. it has an effective spring constant of 4 × 106 n/m, and is observed to compress a distance of 1.39 cm as the car is brought to rest. what was the initial speed of the automobile? answer in units of m/s.

A6,600 kg train car moving at +2.0 m/s bumps into and locks together with one of mass 5,400kg moving at -3.0m/s. what is their final velocity? +0.50 m/s -1.0 m/s +2.5 m/s -0.25 m/s

Why do astronauts in the space shuttle weigh less?

Why is rain likely when warm, moisture-laden air meets cold air? a) the lighter warm air will rise and cool down, causing condensation and rain. b) the cold air moves faster and pushes the warm air away, causing condensation and rain. c) the moisture in the warm air condenses on contact with the cold air, causing rain to fall. d) the cold air mixes with the warm air, reducing its temperature causing moisture to condense.