a ball is launched horizontally from a height of 3.2 m and strikes the ground 4.1 meters away
(measured horizontally). what was the initial velocity of the ball? would a stopwatch be a
reasonable device for measuring the time this takes? why or why not?

A1000-kg weather rocket is launched straight up. the rocket motor provides a constant acceleration for 16-s, then the motor stops. the rocket altitude 20-s after launch is 510-m. you can ignore any effects of air resistance. a. what was the rocket’s acceleration during the first 16-s? b. what is the rocket’s speed as it passes through a cloud 5100-m above the ground?

5g of ammonium nitrate was dissolved in 60g of water in an insulated container. the temperature at the start of the reaction was 23.0°c and at the end it was 19.0°c. calculate the energy absorbed by the reaction.

Achlorine atom has 17 protons and 18 neutrons. what is its mass number? what is its atomic number?