1-a car speeding up at a green light would be speed. 2-a car slowing down at a red light would be speed.
3- a car turning would change , and is still accelerating, even if the speed is constant.

The astronauts on the space shuttle flights experienced an acceleration of 29 m/s2 (about 3 "g's") during lift-off. what upward force must the astronaut's seat apply to the astronaut in order to cause this acceleration? assume the astronaut's mass is 70 kg, and compute this force when the acceleration is near the earth's surface so their weight equals latex: mg m g .