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3 years ago

11

A piece of tape is pulled from a spool and lowered toward a 120-mg scrap of paper. Only when the tape comes within 8.0 mm is the

electric force magnitude great enough to overcome the gravitational force exerted by Earth on the scrap and lift it.

1 answer:

Anton [14]3 years ago

6 0

Answer:

$1.176\times 10^{-3} N$

Upward

Explanation:

We are given that

Mass of scarp paper, $m=120 mg=120\times 10^{-6}kg$

1mg= $10^{-6} mkg$

Distance,d =8 mm= $8\times 10^{-3} m$

Magnitude of electric force = $F_E= w=mg$

Where $g=9.8 m/s^2$

Substitute the values

$F_E=120\times 10^{-6}\times 9.8$

$F_E=1.176\times 10^{-3} N$

Gravitational force act in downward direction.

The electric force acts in opposite direction and magnitude of electric force is equal to gravitational force.

Hence, the direction of electric force is upward.

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Sergio [31]

Answer:They are equal and act in opposite directions.

Explanation:Newton's third law of motion states that for every action there is an equal and opposite reaction. In the case of Bode's rocket, the pressurized air in the bottle forces the water to gush downward out of the bottle, causing the rocket to launch upward into the air. The force of the water gushing downward is equal to the upward force on the rocket. So, the two forces are equal and act in opposite directions.

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3 years ago

Which word means "to get away from something"? <br> a become b dream c escape d practice

klemol [59]

The correct answer is - c. escape.

The word ''escape'' means to get away from something. This word can be used for multiple different situations, and it can refer to both physical and psychological matters.

In a physical sense it can be used to escape from certain unpleasant, or dangerous situation. Example: I have to escape from this prison.

In a psychological sense it can be used to escape, move away, from a certain state of mind. Example: I have to find an escape from my depressive thoughts.

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3 years ago

If an object starts from rest, what is its initial velocity?

Vladimir79 [104]

Answer:

0 m/s

Explanation:

velocity= change in displacement/ time

at rest, the ball does not travel any distance

0/ t

=0

4 0

3 years ago

For heat transfer purposes, an egg can be considered to be a 5.5-cm-diameter sphere having the properties of water. An egg that

Harrizon [31]

Answer:

The time taken is $t = 40007 sec$

Explanation:

From the question we are told that

The diameter of the egg is $d_e = 5.5cm = \frac{5.5}{100} = 5.5*10^{-2}m$

The initial temperature of egg the $T_e = 4.3^{o}C$

The temperature of the boiling water $T_b = 100^oC$

The heat transfer coefficient is $H = 800 W/m^2 \cdot K$

The final temperature is $T_e_f = 74^oC$

The thermal conductivity of water is $k = 0.607 W/m^oC$

The diffusivity of the egg $\alpha = 0.146 * 10^{-6} m^2 /s$

Using one term approximation

We have the

$\frac{T_e_f - T_b}{T_e - T_b} = Ae^{-\lambda ^2 \tau}$

The radius is $r = \frac{5.5*10^ {-2}}{2} =2.75*10^{-2}m$ Note that this radius is approximation to that of a real egg

Now we need to obtain the Biot number which help indicate the value of $A \ and \ \lambda$ to use in the above equation

The Biot number is mathematically represented as

$Bi = \frac{H r}{k}$

Substituting values

$Bi = \frac{800 * 2.75 *10^{-2}}{0.607}$

$= 36.24$

So for this value which greater than 0.1 the coefficient $\lambda_1 \ and \ A_1$ is

$\lambda = 3.06632$

$A = 1.9942$

Substituting this into equation 1 we have

$\frac{74- 100}{4.3 - 100} = 1.9942 e^{-(3.0632^2) \tau}$

$0.2717= 1.9942 e^{-(3.0632^2) \tau}$

$0.2717= 1.9942 e^{-9.383 \tau}$

$0.13624 = e^{-9.383 \tau}$

Taking natural log of both sides

$-1.993 = -9.383\ \tau$

$\tau = 0.2124$

The time required for the egg to be cooked is mathematically represented as

$t = \frac{\tau r^2}{\alpha }$

substituting value is

$= \frac{0.2124 * 2.75 *10^{-2}}{0.146 *10^{-6}}$

$t = 40007 sec$

8 0

3 years ago

_____ is the frictional force needed to slow an object in motion

s2008m [1.1K]

Answer:

<u>Drag force</u> is the frictional force needed to slow an object in motion

Explanation:

8 0

3 years ago

Read 2 more answers