Question

6. When a moving car is brought to a stop with its breaks, its accelermation vector is A. in the same direction as its velocity B. equal to zero C. directed downward D. directed upward E. opposite to the velocity vector 7. A 2 000-kg sailboat experiences an eastward force of 3 000 N by the ocean tide and a wind force against its sails with magnitude of 6 000 N directed toward the northwest (45P N of W What is the magnitude of the resultant acceleration? a. 2.2 m/s b. 2.1 m/s c. 1.5 m/s d. 3.0 m/s 8. A thrown stone hits a window, but doesn't break it. Instead it reverses direction and ends up on the ground below the window. In this case, we know a. the force of the stone on the glass> the force of the glass on the stone. b. the force of the stone on the glass the force of the glass on the stone. c. the force of the stone on the glass < the force of the glass on the stone. d. the stone didn't slow down as it broke the glass. 9. A 140 g baseball traveling initially at 30 m/s is hit by a bat and leaves traveling at 36 m/s in the opposite direction. If the ball was in contact with the bat for 0.013 s, what average force did the bat exert on the bal? A. 1300 N В. 180 N C. 260 N D. 710 N E. 540 N 40,000 kg railroad car moving at 3.1 m/'s collides with a second car of mass 55,000 kg that nitially at rest on the same track. The two cars couple together. What is their speed after the lision? 0.52 m/s 1.3 m/s 2.2 m/s 2.9 m/s 1.8 m/s tatur 70d I atmosphere (76 cm unat in ite new yolu

Answer 1

here,

6)

when a car is brought to rest by applying the brakes

the final speed is zero

and less than the initial speed

the acceleration , a = change in velocity /time

so, the change in velocity is negative

and acceleration is also negative

so, the correct option is the acceleration is E) opposite to the velocity vector