Name: gravity-driven free fall motion
Uploaded: 2023-04-30T10:51:06.000Z
Duration: 1 min 5 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Physics

motion-and-stability-forces-and-interactions

Motion and Stability- Forces and Interactions

PS.Phy.1.1

Free-falling Bodies: Example

Rappelons que lorsqu’un objet tombe vers le sol et n’est influencé que par la gravité, on dit qu’il est en chute libre. Sous la gravité terrestre, un objet tombe avec une accélération constante, connue sous le nom d'accélération due à la gravité.
Les équations cinématiques de l’accélération constante sont utilisées pour résoudre les problèmes de corps en chute libre.
Par exemple, une pierre est lâchée librement du haut d’une falaise dans une rivière. Quelle sera sa position et sa vitesse après 5 secondes ?
Les grandeurs connues sont la position initiale, la vitesse initiale, l’accélération due à la gravité et le temps.
Si l’on considère la coordonnée verticale de l’axe des y, le sommet de la falaise est l’origine et la direction ascendante est négative. Les quantités inconnues sont la position et la vitesse de la pierre après 5 secondes.
En substituant les valeurs connues dans les équations cinématiques, on obtient 122,5 mètres comme distance parcourue et 49 mètres par seconde comme vitesse de la pierre.

corps en chute libre : exemple

Un objet qui tombe sans résistance de l'air, sous l'influence de la force gravitationnelle, est dit être en chute libre. Pour les corps en chute libre, l'accélération due à la gravité est constante, indépendamment de leur masse. La chute libre est vécue non seulement par les objets tombant vers le bas, mais aussi par tous les objets dont le mouvement est influencé uniquement par la force gravitationnelle. La dynamique du mouvement en chute libre peut être calculée en utilisant les équations cinématiques du mouvement, puisque l'accélération de la chute libre est constante.

L'accélération subie par tous les objets en chute libre est constante ; par conséquent, deux objets lâchés du même niveau et du même endroit sur Terre tomberont au sol à la même vitesse, à condition que la résistance de l'air soit négligée. De même, si deux objets sont lâchés successivement, alors le temps nécessaire pour atteindre le sol sera le même. Cependant, la vélocité de l'objet lâché en premier sera toujours supérieure à la vitesse de l'objet lâché ensuite.

Quelques exemples de la vie réelle de la chute libre comprennent :

<ol>
	<li>Le parachutisme et le saut à l'élastique</li>
	<li>Un météoroïde accélérant vers le centre de la Terre</li>
	<li>Un vaisseau spatial en orbite autour de la Terre</li>
	<li>Le mouvement parabolique d'un objet dans un espace à deux dimensions</li>
</ol>

Ce texte est adapté de <a href="https://openstax.org/books/university-physics-volume-1/pages/3-5-free-fall">Openstax, University Physics Volume 1, Section 3.5: Free-fall</a><a href="https://openstax.org/books/university-physics-volume-1/pages/3-6-finding-velocity-and-displacement-from-acceleration">.</a>

Corps en chute libre : Exemple

On dit qu’un objet tombant sans aucune résistance de l’air sous l’influence de la force gravitationnelle est en chute libre. Pour les corps en chute libre, le ...

Education

Enseignement

JoVE Core

Physique

Unit 1

Unité 1

Motion Along a Straight Line

Mouvement rectiligne

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

gravity-driven free fall motion

Gravity-driven free fall motion is the motion of an object when gravity is the only force acting on it and air resistance is absent. In this case, the object is in free-fall. The acceleration due to gravity stays constant, no matter how much the object weighs.

Free-fall is not limited to objects moving straight down. It also includes motion that is affected only by gravity. Because the acceleration is constant, the motion can be described with kinematic equations.

Objects dropped from the same height and location on Earth will reach the ground at the same speed if air resistance is neglected. If two objects are dropped one after the other, they will take the same time to fall. The object released first will still have a greater velocity than the object released later.

Free-fall appears in many real situations. Examples include skydiving and bungee jumping, a meteoroid moving toward Earth’s center, a spacecraft in Earth’s orbit, and the projectile motion of an object in two-dimensional space.

Gravity-Driven Free Fall Motion

position and displacement

Reference Frames and Motion in a Line

Position in straight-line motion depends on a frame of reference. A frame of reference is an arbitrary set of axes used to describe an object’s position and motion. It gives meaning to where something is located at a particular time. Earth is often used as the reference frame. In that case, we describe an object’s position relative to stationary objects on Earth. A rocket launch can be described this way. A cyclist’s position can also be described relative to the buildings they pass. <br...

average velocity

Average Velocity and Average Speed

Average velocity and average speed help describe motion in kinematics. To compare motion over time, we use the time variable. Time lets us track an object’s position and how fast that position changes. For motion between two points, each position x_i is paired with a time t_i. When the details of motion at each instant are not important, we use average velocity. Average velocity is a vector quantity, so it includes direction. It is found by dividing total displacement, Δx, by the time...

instantaneous velocity - i

Instantaneous Speed and Direction

Instantaneous velocity describes how fast an object is moving at a specific instant. It gives the motion of a particle at one point in time or at one point along its path. Average velocity over a time interval cannot show this level of detail. Instantaneous velocity, often written as v x , is the limit of average velocity as the elapsed time approaches zero. It can also be found as the derivative of x with respect to t . Like average velocity, it is a vector with dimensions of length per unit...

instantaneous velocity - ii

Instantaneous Velocity from Position Graphs

Instantaneous velocity describes how fast an object is moving at a specific moment along its path. It is the limit of average velocity as the elapsed time approaches zero. It can also be written as the derivative of displacement with respect to time. Like average velocity, instantaneous velocity is a vector, so it has both size and direction. Its units are length per unit time. Instantaneous velocity can be positive or negative. A position-time graph can show it at any point on the motion...

average acceleration

Average Acceleration and Velocity Change

Average acceleration describes how velocity changes over time. In physics, acceleration is not just about speeding up. It also includes slowing down and changing direction. Since velocity is a vector, it has both magnitude and direction. A change in velocity can come from a change in speed, a change in direction, or both. For example, a runner may travel at 10 km/h due east, stop, reverse direction, and then continue at 10 km/h due west. Even though the speed is the same, the velocity has...

instantaneous acceleration

Negative Acceleration and Instant Speed Change

Acceleration shows how velocity changes, and it does not always point in the same direction as motion. When an object slows down, its acceleration points opposite to its motion. This is often called deceleration, but that term can cause confusion because deceleration is not a vector and does not point in a specific direction in a coordinate system. A subway train is a simple example. When the train slows down, it is still accelerating, but the acceleration points opposite to the direction it...

kinematic equations - i

Velocity from Constant Acceleration

Velocity from constant acceleration shows how an object’s speed and direction change when the acceleration stays the same. The first kinematic equation connects initial velocity, acceleration, and time for motion with constant acceleration. It helps describe how velocity changes at a steady rate throughout the motion. The equation matches common sense in several cases. If acceleration is zero, the final velocity is the same as the initial velocity, so the object keeps a constant velocity. If...

kinematic equations - ii

Using the Second Kinematic Equation

The second kinematic equation relates an object’s final position to its initial position, its starting velocity, and the extra distance gained as velocity changes. It is used only when acceleration stays constant during the motion. That makes it useful for straight-line motion problems with a steady rate of acceleration. A car merging onto a 200 m freeway ramp is a good example. In the example, the car starts at 10 m/s and accelerates at 2 m/s². The known values are the distance, the initial...

kinematic equations - iii

Constant-Acceleration Kinematics Formulas

Constant-acceleration kinematics formulas connect an object’s motion when acceleration stays the same. They help describe how velocity and position change over time. These equations are useful for solving motion problems and for understanding the relationships among distance, time, velocity, and acceleration. The third kinematic equation does not use time as a variable. Instead, it gives final velocity in terms of acceleration and the distance over which that acceleration acts. The fourth...

kinematic equations: problem solving

Solving Constant Acceleration Motion Problems

Solving one-dimensional motion problems with constant acceleration starts with identifying the known quantities and choosing the right kinematic equation. A kinematic equation is a motion formula that relates displacement, velocity, acceleration, and time. Depending on what is known and unknown, you may need one equation or two equations to find the answer. In many problems, the number of equations needed matches the number of unknowns. Two-body pursuit problems are different. They always...

free-falling bodies: introduction

Gravity and Free-Fall Motion

Gravity and free-fall motion explain how objects move when only Earth’s gravity acts on them. In free-fall, the motion is caused by gravitational force, and air resistance is neglected. This means the object accelerates toward Earth’s center. This result is surprising because everyday experience includes friction and air resistance. We often expect lighter objects to fall more slowly than heavier ones. People held that idea until Galileo Galilei proved that mass does not change the...

free-falling bodies: example

Gravity-driven free fall motion is the motion of an object when gravity is the only force acting on it and air resistance is absent. In this case, the object is in free-fall. The acceleration due to gravity stays constant, no matter how much the object weighs. Free-fall is not limited to objects moving straight down. It also includes motion that is affected only by gravity. Because the acceleration is constant, the motion can be described with kinematic equations. Objects dropped from the...

velocity and position by graphical method

velocity-and-position-by-graphical-method

Acceleration Graphs for Motion Prediction

Acceleration graphs can be used to find velocity and position over time. The area under an acceleration-time graph gives the change in velocity. The area under a velocity-time graph gives the change in position, or displacement. A real example is an airplane using an inertial navigation system. Before takeoff, the pilot enters the airplane’s initial position and velocity. The system then uses acceleration data to calculate the airplane’s velocity and position during flight. When acceleration...

velocity and position by integral method

Finding Motion from Acceleration Data

Velocity and position can be found from acceleration using integral calculus. When acceleration is known as a function of time, the velocity function comes from integrating acceleration. The position function then comes from integrating velocity. For constant acceleration, these integral steps match the first and second kinematic equations for velocity and position. The example in this lesson uses a motorboat that is moving at 5.0 m/s and then begins to slow down as it approaches the dock. Its...

key terms and concepts

Learn how free fall works when gravity is the only force acting on an object, and see examples like skydiving, meteoroids, orbit, and projectile motion.

Gravity-Driven Free Fall Motion | JoVE K12

physics

JoVE Core Physique présente plusieurs branches de la physique fondamentale grâce à des vidéos animées concises et faciles à comprendre ; cela inclut: la cinématique, la dynamique, la mécanique des fluides, la mécanique statique, les ondes et l'acoustique. En parallèle, les vidéos de scientifiques à l'action démontrent l'application de concepts associés à ces domaines dans des expériences de recherche classiques et originales réalisées dans des laboratoires modernes du monde entier.

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Ohio’s Learning Standards and Model Curriculum

Motion

Problem Solving

Tennessee Academic Standards

High School

Motion and Stability: Forces and Interactions

PHYS.PS2.5

PHYS.PS2.7

Energy

PHYS.PS3.3

Virginia  Standards of Learning

HIgh School

Physical Science

PS.8

PS.8.a

PH.2

PH.2.b

Alabama Course of Study Science

9-12.P.1.1.b

Florida Department of Education

SC.912.P.12

SC.912.P.12.2

Georgia Standards of Excellence

SPS8.

Falling Objects

Position and Displacement

The position of an object defines its location relative to a convenient frame of reference at any particular time. A frame of reference is an arbitrary ...

Average Velocity

To calculate the other physical quantities in kinematics, we must introduce the time variable. The time variable allows us not only to state the position ...

Instantaneous Velocity - I

The average velocity during a time interval cannot tell us how fast or in what direction a particle is moving at any given time during the interval. To ...

Instantaneous Velocity - II

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Average Acceleration

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Instantaneous Acceleration

Acceleration is in the direction of the change in velocity, but it is not always in the direction of motion. When an object slows down, its acceleration ...

Kinematic Equations - I

When an object moves with constant acceleration, the velocity of the object changes at a constant rate throughout the motion. The kinematic equations of ...

Kinematic Equations - II

The second kinematic equation expresses the final position of an object in terms of its initial position, the distance traveled with the initial constant ...

Kinematic Equations - III

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Free-falling Bodies: Introduction

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Velocity and Position by Integral Method

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Use models (graphs, equations, diagrams) to infer motion in one dimension.

Position and Displacement Vectors

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average-and-instantaneous-velocity-vectors

Average and Instantaneous Velocity Vectors

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Acceleration Vectors

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Direction of Acceleration Vectors

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Projectile Motion

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Projectile Motion: Equations

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Projectile Motion: Example

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Relative Velocity in One Dimension

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Relative Velocity in Two Dimensions

Relative velocity is the velocity of an object as observed from a particular reference frame, or the velocity of one reference frame with respect to ...

Use models (graphs, equations, diagrams) to infer motion in two dimensions.

PS.Phy.1.2

Force

Forces affect every moment of our life. Our bodies are held to the Earth by force, and they are held together by the forces of charged particles. When we ...

Types of Forces

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Free Body Diagrams: Examples

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Use free body models to qualitatively and quantitatively analyze systems of forces in one dimension and two dimensions.

PS.Phy.2.1

Newton's First Law: Introduction

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Newton's First Law: Application

Experience suggests that an object at rest remains at rest if left alone, and that an object in motion tends to slow down and stop unless some effort is ...

Internal and External Forces

Newton&#39;s first law states that a net external force causes a change in motion. External forces act on an object or system, originating outside of the ...

Newton's Second Law

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Mass and Weight

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Weightlessness

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Apparent Weight

True weight is the measure of the gravitational force acting on an object. However, if the object accelerates, its measured weight is different from its ...

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Newton's Third Law: Introduction

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Newton's Third Law: Examples

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First Law: Particles in Two-dimensional Equilibrium

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Second Law: Motion under Same Force

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Tension

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Carry out investigations to explain the interactions of forces on an object according to Newton's Laws of Motion.

PS.Phy.2.2

Analyze the motion of objects using time, distance, displacement, speed, velocity, and acceleration.

Gravity-Driven Free Fall Motion

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