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3 years ago

What does the force diagram look like for a book at rest on a desk?

1 answer:

7 0

An arrow representing the weight of the book acts downwards on the table. An arrow of equal magnitude, but opposite direction represents the normal reaction force of the table on the book.

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Three forces act on a moving object. One force has a magnitude of 83.7 N and is directed due north. Another has a magnitude of 5

LekaFEV [45]

Answer:

$|\vec{F}_3| = 102.92 \ N$

$\theta = 57 \° 24 ' 48''$

Explanation:

For an object to move with constant velocity, the acceleration of the object must be zero:

$\vec{a} = \vec{0}$ .

As the net force equals acceleration multiplied by mass , this must mean:

$\vec{F}_{net} = m \vec{a} = m * \vec{0} = \vec{0}$ .

So, the sum of the three forces must be zero:

$\vec{F}_1 + \vec{F}_2 + \vec{F}_3 = \vec{0}$ ,

this implies:

$\vec{F}_3 = - \vec{F}_1 - \vec{F}_2$ .

To obtain this sum, its easier to work in Cartesian representation.

First we need to define an Frame of reference. Lets put the x axis unit vector $\hat{i}$ pointing east, with the y axis unit vector $\hat{j}$ pointing south, so the positive angle is south of east. For this, we got for the first force:

$\vec{F}_1 = 83.7 \ N \ (-\hat{j})$ ,

as is pointing north, and for the second force:

$\vec{F}_2 = 59.9 \ N \ (-\hat{i})$ ,

as is pointing west.

Now, our third force will be:

$\vec{F}_3 = - 83.7 \ N \ (-\hat{j}) - 59.9 \ N \ (-\hat{i})$

$\vec{F}_3 = 83.7 \ N \ \hat{j} + 59.9 \ N \ \hat{i}$

$\vec{F}_3 = (59.9 \ N , 83.7 \ N )$

But, we need the magnitude and the direction.

To find the magnitude, we can use the Pythagorean theorem.

$|\vec{R}| = \sqrt{R_x^2 + R_y^2}$

$|\vec{F}_3| = \sqrt{(59.9 \ N)^2 + (83.7 \ N)^2}$

$|\vec{F}_3| = 102.92 \ N$

this is the magnitude.

To find the direction, we can use:

$\theta = arctan(\frac{F_{3_y}}{F_{3_x}})$

$\theta = arctan(\frac{83.7 \ N }{ 59.9 \ N })$

$\theta = 57 \° 24 ' 48''$

and this is the angle south of east.

7 0

3 years ago

Ned the skydiver weighs 600 N and is falling at terminal speed. That is, he has sped up until air resistance has built up so muc

natali 33 [55]

Answer:

The work done is 120000 J.

Explanation:

Given that,

Weight = 600 N

Distance = 200 m

We need to calculate the work done

Using formula of work done

$W=F\times d$

Where, F = force

d = distance

Put the value into the formula

$W=600\times200$

$W=120000\ J$

Hence, The work done is 120000 J.

7 0

4 years ago

A child pushes horizontally on a box of mass m which moves with constant speed v across a horizontal floor. The coefficient of f

dexar [7]

Answer:

Explanation:

Given

mass of box is m

speed of box is v

coefficient of friction $\mu =\frac{1}{4}=0.25$

Box is moving at a constant speed i.e. Net Force on box is zero

i.e. Frictional Force and Force Applied are Equal

$F=f_r=\mu mg$

The Rate at which power is generated is

$P=F\cdot v$

$P=\mu mg\cdot v$

$P=0.25mgv$

4 0

3 years ago

Explain how machines can be useful if the output is always less than the input work

Anni [7]

Because: Some of the work done by the machine is used to overcome the friction created by the use of the machine. ... Work output can never be greater than work input. Machines allow force to be applied over a greater distance, which means that less force will be needed for the same amount of work.

6 0

3 years ago

The rate at which work is done is called ____.

alekssr [168]

D. Power. The unit of power is watt.

6 0

3 years ago