Physics I - Concepts

A ball is thrown vertically upward from the surface of the earth. Consider the following quantities: 1- the speed of the ball 2- the velocity of the ball 3- the acceleration of the ball Which of these is (are) zero when the ball has reached its maximum height?

1 & 2

Which one of the following situations is NOT possible

A body travels with a constant velocity and a time-varying acceleration.

Ball A is dropped from rest from a window. At the same time, ball B is thrown downward and ball C is thrown upward form the same window. Which statement concerning the ball is necessarily true if air resistance is neglected?

All three have the same acceleration: g

A rock is thrown vertically upward from the surface of the earth. The rock rises to some maximum height and falls back toward the surface of the earth. Which one of the following statements concerning this situation is true if air resistance is neglected?

The ball is a freely falling body for the duration of the flight

An object moving along a straight line is decelerating. Which one of the of the following statements concerning the object's accelerates is necessarily true

The direction of the acceleration is in the direction opposite of the velocity ( ALWAYS in opposite direction when decelerating)