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.

b. lifting dumbbell weight at 20-degree angle from the body after a 45-degree angle

we need to know the time interval during which the force acts. impulse of force = momentum change