Glenn Hopkins
2022-07-22
Answered

Define net force, external force, and system. Apply Newton’s second law to determine the weight of an object

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kamphundg4

Answered 2022-07-23
Author has **20** answers

Net force can be defined as the vector sum of the forces acting on a particular object.

Net external force can be defined as the vector sum of all the external forces acting on a particular object.

A system can be defined by the boundaries of an object or collection of objects being observed. Any force that originates from outside a system is considered external forces.

According to the Newton’s second law of motion, the net force acting on an object is directly proportional to the acceleration of the object.

${F}_{\text{net}}=ma$

Consider a ball of mass 10kg under free fall. Then the weight of the ball can be obtained as

${F}_{\text{net}}=mg\phantom{\rule{0ex}{0ex}}=(10\text{kg})(9.8{\text{m/s}}^{2})\phantom{\rule{0ex}{0ex}}=98\text{N}$

Net external force can be defined as the vector sum of all the external forces acting on a particular object.

A system can be defined by the boundaries of an object or collection of objects being observed. Any force that originates from outside a system is considered external forces.

According to the Newton’s second law of motion, the net force acting on an object is directly proportional to the acceleration of the object.

${F}_{\text{net}}=ma$

Consider a ball of mass 10kg under free fall. Then the weight of the ball can be obtained as

${F}_{\text{net}}=mg\phantom{\rule{0ex}{0ex}}=(10\text{kg})(9.8{\text{m/s}}^{2})\phantom{\rule{0ex}{0ex}}=98\text{N}$

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How to calculate acceleration due to gravity in a 3D $N$-Body system?

How do you calculate acceleration due to gravity for objects in 3D space?

My current understanding for the force due to gravity on object $i$ from object $j$ is

${\mathbf{F}}_{g}=({\mathbf{r}}_{j}-{\mathbf{r}}_{i}){m}_{j}{m}_{i}G/|{\mathbf{r}}_{j}-{\mathbf{r}}_{i}{|}^{3}$

where ${\mathbf{r}}_{i}$ and ${\mathbf{r}}_{j}$ are the 3D position vectors of object $i$ and object $j$

Is this right? If not, what is?

Also, should

$|{\mathbf{r}}_{j}-{\mathbf{r}}_{i}{|}^{3}$

be the same as $[({x}_{j}-{x}_{i}{)}^{2}+({y}_{j}-{y}_{i}{)}^{2}+({z}_{j}-{z}_{i}{)}^{2}{]}^{3/2}$ or the vector $[|{x}_{j}-{x}_{i}|,|{y}_{j}-{y}_{i}|,|{z}_{j}-{z}_{i}|]$ cubed?

How do you calculate acceleration due to gravity for objects in 3D space?

My current understanding for the force due to gravity on object $i$ from object $j$ is

${\mathbf{F}}_{g}=({\mathbf{r}}_{j}-{\mathbf{r}}_{i}){m}_{j}{m}_{i}G/|{\mathbf{r}}_{j}-{\mathbf{r}}_{i}{|}^{3}$

where ${\mathbf{r}}_{i}$ and ${\mathbf{r}}_{j}$ are the 3D position vectors of object $i$ and object $j$

Is this right? If not, what is?

Also, should

$|{\mathbf{r}}_{j}-{\mathbf{r}}_{i}{|}^{3}$

be the same as $[({x}_{j}-{x}_{i}{)}^{2}+({y}_{j}-{y}_{i}{)}^{2}+({z}_{j}-{z}_{i}{)}^{2}{]}^{3/2}$ or the vector $[|{x}_{j}-{x}_{i}|,|{y}_{j}-{y}_{i}|,|{z}_{j}-{z}_{i}|]$ cubed?

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A 2.0 kg book is lying on a 0.75-m-high table. You pick it up and place it on a bookshelf 2.3 m above the floor. During this process,

How much work does gravity do on the book?

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The gravitational force between two objects is 2400 N. What will be the gravitational force between the objects if the mass of one object is doubled?

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Two balls have their centers 2.0 m apart. One ball has a mass of 8.0 kg. The other has a mass of 6.0 kg. What is the gravitational force between them?

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A proton with an initial speed of 800,000 m/s is brought to rest by an electric field. a. Did the proton move into a region of higher potential or lower potential? b. What was the potential difference that stopped the proton? c. What was the initial kinetic energy of the proton, in electron volts?