A group of bike riders took a 4.0-hour trip. During the first 3.0 hours, they traveled a total of 50. kilometers, but during the last hour they traveled only 10. kilometers. What was the group's average speed for the entire trip?
A.
40. km/hr
B.
30. km/hr
C.
15 km/hr
D.
60. km/hr
2.
One car travels 40. meters due east in 5.0 seconds, and a second car travels 64 meters due east in 8.0 seconds. During their periods of travel, the cars definitely had the same
A.
Total displacement
B.
Average velocity
C.
Average speed
D.
Change in momentum
3.
The speed of a car is decreased uniformly from 30. meters per second to 10. meters per second in 4.0 seconds. The magnitude of the car's acceleration is
A.
5.0 m/s2
B.
10. m/s2
C.
40. m/s2
D.
20. m/s2
4.
A car having an initial velocity of 12 meters per second east slows uniformly to 2 meters per second east in 4.0 seconds. What is the acceleration of the car during this 4.0-second interval?
A.
2.5 m/s2 west
B.
2.5 m/s2 east
C.
6.0 m/s2 east
D.
6.0 m/s2 west
5.
Two cars, A and B, are 400. meters apart. Car A travels dueeast at 30. meters per second on a collision course withcar B, which travels due west at 20. meters per second. Howmuch time elapses before the two cars collide?1) 2) 8.0 s3) 20. s4) 40. s