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Question

A ball is thrown at an angle of 45 degrees above the horizontal. Which of the following best describes the acceleration of the ball from the instant after it leaves the thrower's hand until the time it hits the ground?

  1. Always in the same direction as the motion, initially positive and gradually dropping to zero by the time it hits the ground

  2. Initially positive in the upward direction, then zero at maximum height, then negative from there until it hits the ground

  3. Always in the opposite direction as the motion, initially positive and gradually dropping to zero by the time it hits the ground

  4. Always in the downward direction with the same constant value

Question by OpenStax is licensed under CC BY 4.0.
Final Answer

(d)

Solution Video

OpenStax College Physics Solution, Chapter 3, Problem 1 (Test Prep for AP® Courses) (0:40)

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Video Transcript
This is College Physics Answers with Shaun Dychko. When a ball is launched at a forty-five degree angle or thrown at any angle into the air, despite having this curved path and a velocity that is changing as it goes, the acceleration is constant at all times. It is always 9.8 meters per second squared directed downwards and it never changes. So while the position changes and the velocity changes, acceleration does not. It's always in a downward direction with the same constant value.