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## Pixar in a Box

### Course: Pixar in a Box>Unit 7

Lesson 2: The physics of particle systems

# Force and acceleration

What's the different between a wind force and the force due to gravity? This video covers both Newton's second law of motion and law of gravity. Newton's second law tells us that force equals mass times acceleration. Gravity's force is independent of mass, making objects fall at the same rate.

## Want to join the conversation?

• At , Matt mentions that Newton came to the conclusion that not only force was proportional to mass times acceleration, and that Newton proved that force is EQUAL to mass times acceleration. How did he figure that out?
• We simply define the Newton (N) such that the constant of proportionality is 1. If we wanted we could define a different unit and introduce a proportionality constant, but what would be the point.

However it is worth noting that because we have definied the proportionality constant as one here, this restricts our representation of other equations like Newton's gravitational force equation between two masses, where a constant called G has to be added in to make the gravitational force consistent with the force of acceleration the masses experience.
• who here died on the inside at
• if you rolled the balls down a hill, which one will accelerate faster?
• Galileo also did this experiment, and found that the heavier ball rolled faster.
(He used his heart rate to measure it, so he might have got excited and his heart sped up... XD).
• how does gravity work
• At 9.82 meters per second
(1 vote)
• in the video the persons talked about newton`s laws. I remember Albert Einstein made some changes to Newton's laws. Does this changes anything or am i mistaken.
• At it states that "a~f/m". If I would substitute the "f" in the equation by "a" (since they are proportionally the same) it shows an incorrect equation "a~a/m". Can someone tell me why the equation "a~f/m" is true, or what am I doing wrong?
• Why did both the balls which were thrown towards the ground from leaning tower of pissa fell with same acceleration? (Newton's experiment)
• They were dropped, not thrown. Also, they have the same acceleration because the acceleration due to gravity is the same for all objects. He explained why in the video, but I'll try to explain a little differently.

1) An object with more mass is harder to move than an object with less mass.

This means that an object with more mass requires a greater force to move it. So, picking up a plate is easier than picking up a monitor.

2) When it comes to gravity, a larger mass is affected by gravity more strongly.

For instance, the force that the Earth exerts on you is much less than the force that the Earth exerts on the moon.

Facts one and two (sort of) cancel each other out, so you end up having all objects fall at the same acceleration due to gravity (assuming that we do not take air resistance into account).
(1 vote)
• I Wonder Why There Is Wind Force On An Atomic Level? Wouldn't That Just Be Oxygen Hitting The Particles?