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2 years ago

Why are the action and reaction forces described by Newton’s third law of motion excluded in the free-body diagram of an object?

Physics

2 answers:

Lorico [155]2 years ago

6 0

The correct answer is:

B. They act on different objects, so they would not appear together.

Let's take for example a box sitting on a table. If we draw the free-body diagram of the box, we would draw two forces:

- the weight of the box (downward)

- the normal reaction of the table on the box (upward)

However, this is not a pair of action-reaction forces as described in Newton's third law. In fact, the correct action-reaction pair would be:

- weight of the box (=gravitational force exerted by the Earth on the box)

- gravitational force exerted by the box on the Earth

We see that these two forces act on two different objects (the first one on the box, the second one on the Earth), so they do not appear in the same free-body diagram.

umka2103 [35]2 years ago

4 0

B. <span>They act on different objects, so they would not appear together.</span>

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A mine car (mass=390 kg) rolls at a speed of 0.50 m/s on a horizontal track, as the drawing shows. A 250-kg chunk of coal has a

Nady [450]

Answer:

v=0.60 m/s

Explanation:

Given that

m ₁= 390 kg ,u ₁= 0.5 m/s

m₂ = 250 kg ,u₂ = 0.76 m/s

As we know that if there is no any external force on the system the total linear momentum of the system will be conserve.

Pi = Pf

m ₁u ₁+m₂u₂ = (m₂ + m ₁ ) v

Now putting the values in the above equation

390 x 0.5 + 250 x 0.76 = (390 + 250 ) v

$v=\dfrac{390\times 0.5+250\times 0.76}{390+250}\ m/s$

v=0.60 m/s

Therefore the velocity of the system will be 0.6 m/s.

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3 years ago

How is the surface area of an average person is 2m^2 in the chapter pressure

11Alexandr11 [23.1K]

Answer:

We have to show surface area $=2m^2$ ,with few conditions that is by considering Force $=200000\ N$ and Pressure $=100000\ Pa$ to be respectively.

Explanation:

The atmospheric pressure is $=10^{5}\ Pa$ on Earth's surface.

The magnitude of the force exerted on a person by the atmosphere is $=2\times 10^{5}\N (or)\ 200kN\ (or)\ 20\ ton$ .

Now to calculate surface area we can find it from $pressure=\frac{force}{area}$ and re-arranging it to.

$area=\frac{force}{pressure}$

So plugging the values,

Surface area $=\frac{20000}{10000}=2\ m^{2}$

Hence from the above calculations we can say that surface area is $2m^2$ .

So the surface area of an average person can be said to have $2m^2$ , using the concept of pressure and force.

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2 years ago

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In a physics lab experiment, a spring clamped to the table shoots a 22g ball horizontally. When the spring is compressed 21cm ,

worty [1.4K]

a square and a triangle I think

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3 years ago

When you lift an object, you add the energy of lifting to the object.<br> Tor F

PtichkaEL [24]

It's true, when we lift an object we add energy to it.

because, when we lift an object by applying force , the object attains a height and hence the energy gets stored in it, in the form gravitational potential energy .

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2 years ago

choose the correct anwer 9: the range of the gravitional force is given by A: 10_2m B:10_15m C: infinite D: 10_10m

frosja888 [35]

Answer:

The answer is C

Explanation:

The magnitude of the gravitational force depends inversely on the square of the radial distance between the centers of the two masses. Thus, essentially, the force can only fall to zero, when the denominator that is r becomes infinite.

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2 years ago