Introduction to Free-Fall and the Acceleration due to Gravity

In this lesson we extend our knowledge of Uniformly Accelerated Motion to include freely falling objects. We talk about what Free-Fall means, how to work with it and how to identify and object in Free-Fall. Today I get to introduce so many of my favorites: the medicine ball, the vacuum that you can breathe and, of course, little g.

0:00 Intro
0:22 An Example of An Object in Free-Fall
0:54 Textbook definition of a freely falling object
1:11 We have not defined a "Force" so this is how we define Free-Fall
2:07 No Air Resistance (The Vacuum that You Can Breathe!)
3:10 What does it mean to be in Free-Fall? (The Acceleration due to Gravity)
4:41 The Acceleration due to Gravity - Not on Earth
5:24 g is not constant on Earth. Very close, but not quite
5:56 Common Misconception: Objects moving upward can be freely falling
6:35 Free-Fall is Uniformly Accelerated Motion
7:27 What does the negative mean in -9.81 m/s^2?
7:57 Is "g" positive or negative?
9:01 How can "g" be not constant and we can use UAM?
10:03 Does mass effect the acceleration due to gravity?
10:47 The Review

Want Lecture Notes?

Previous Video: Reviewing One Dimensional Motion with the Table of Friends

Next Video: Apollo 15 Feather and Hammer Drop

[arafe-zawad-sajid]

I hated physics my whole life and here I am enjoying each and everyone of your videos! Not only they are informative but also they are so entertaining. Thank you for such a great contribution for students like me. Cheers man! You are the best teacher ever :D

[napialex]

the best short and concise physics tutorial in the universe.

[FlippingPhysics]

Divneet k, the acceleration due to gravity is always directed down towards the center of the planet. We usually define up as positive and down as negative, therefore the acceleration due to gravity is negative because it is always down, regardless of the direction the object is moving.

[heyhey]

YOU ARE AMAZING AT EXPLAINING THINGS IN A VERY SIMPLE AND CLEAR MANNER!!!

[polarise]

Your videos are GREAT! Concise, with very good explanation of the concepts, engaging and funny. Thank you so much.

[xXWhateverXx]

I absolutely love all of the effort you put into these videos. Your explanations (and teaching) is better than my college professor. You're getting me through college physics.

[divneet]

you rock! please keep uploading more, you`re one of the best teachers<who teaches physics practically> . i wanted to clarify if my understanding is right, so yeah acceleration due to gravity will be positive if the ball is thrown downwards as it is in the direction of acceleration due to gravity and it`ll be negative if the ball is thrown upwards as its against the force of gravity right? but then i saw your videos and its the opposite. i got really confused.

[lnskyy]

Just a quick tip!
Why is a ball thrown upwards considered free falling even though our hand exerted a force upon it?
When you let go of the ball, you are not exerting a force upon it anymore. The velocity of the ball would stay the same and continue to space if there were no forces acting upon it (inc gravity). The velocity of the ball changes because gravity becomes the sole force acting upon it and the ball is now free falling. The ball does not 'carry the force' or anything. The ball has a positive (non zero) velocity at first when it is moving upwards due to the force that had been on the ball but there is no force acting on the ball anymore.

[teesanders]

Thank you for clarifying the constant "g."

[aaeccs]

This helped me so much! you're teaching style is the best I've seen! keep up the good work

[josephpayago]

you deserve a million subscribers. Your videos are absolutely amazing, enjoyable and informative. I wish our professors are as passionate as you are in teaching us. :)

[alexandrasiegel]

Wow! These videos are amazing in science Class and I have such a great time watching all of you educational videos!!

[niaris]

i wish i knew this existed before i took the quizzes, now im taking my exams tomorrow. THIS IS AWESOME! I'M FINALLY LEARNING THINGS!

[Neverknownone]

wow you are a great teacher with lots of enthusiasm. thanks

[tisthedamndoc]

Just came here to thank you🙏 for these awesome videos...they are so helpful and fun to watch..😊😊

[DMiddleEast]

Thank you so much, that really helped ! And it was fun to watch as well...

[Ginger]

Thank you so much for all the effort of making these videos easy to understand and funny! I wish I have class with billy, bobby and bo!

[emersonruizrico]

This video is great!
I learned a lot from this..
:)

[samyang]

Hi i am studying for ap physixs exam in 2020 and I am using your videos to study. I see there are a lot of videos in this playlist. Which are the key videos that I should watch and review for the content in this ap physics exam? Thank you, these videos are so helpful

[drishtysharma]

flipping physics it is really awesome to watch and i really enjoyed the concepts of physics..well ty for making physics interesting...