A ball on a frictionless plane is swung around in a circle at constant speed. The acceleration points in the same direction as the velocity vector. a. True
b. False

False

Explanation:

You have a circle so think back to circular motion. Theres 2 directions, centripetal and tangential. The problem tells you there's a constant tangential speed so tangential acceleration is 0. However there is a centripetal acceleration acting on the ball that holds it in its circular motion (i.e. tension, or gravity). Since centripetal is perpendicular to the tangential direction, acceleration and velocity are in different directions.

d = 1,029 m

Explanation:

When the young man shoots the rifle the sound travels in all directions, if the young man is at the same distance from the two walls, as the speed of the wave is constant, he takes the same time to go to the wall and return for which he hears a single echo.

To calculate the distance let's use the uniform motion relationships

        v = d / t

        d = v t

As the speed is constant, the time to reach the wall is the same as it takes to go from the wall to the young man,

         t = to / 2

         t = 6/2

         t = 3 s

         d = 343 3

         d = 1,029 m