Atrain engineer started the train from a standstill and sped up to 5 meters per second, she then rounded a corner at a constant speed. she then sped the train up to 10 meters per second on the next straightaway. next, the train chugged around another bend at 10 m/sec, and then its speed slowed to 5 meters per second after coming out of the bend. finally, the train reached the station, and the engineer applied the brakes and brought the engine to a stop. how many times did the train accelerate?

Askydiver weighing 140 lb (including equipment) falls vertically downward from an altitude of 19,000 ft and opens the parachute after 18 s of free fall. assume that the force of air resistance, which is directed opposite to the velocity, is of magnitude 0.55|v| when the parachute is closed and is of magnitude 14|v| when the parachute is open, where the velocity v is measured in ft/s. assume that acceleration due to gravity has magnitude 32 ft/s/s; remember that weight is the product of mass and gravitational acceleration. (a) find the speed of the skydiver when the parachute opens. (b) find the distance fallen before the parachute opens. (c) what is the limiting velocity vl after the parachute opens? (d) determine how long the sky diver is in the air after the parachute opens. (e) plot the graph of velocity versus time from the beginning of the fall until the skydiver reaches the ground.

What are the three ways that an object can accelerate

If gases like carbon dioxide and methane make up less than 1% of the total atmosphere, why is it important for scientists to monitor changes in percentages of these gases?