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3 years ago

6. Why are there some areas of the country where wind power is not the best option? Explain.

Physics

2 answers:

zhuklara [117]3 years ago

6 0

Not all states and parts of the country re suitable for wind power because the weather isnt always stable

Advocard [28]3 years ago

4 0

Before you spend the ginormous amount of money to buy the land and build the windmills, you need to make sure you're building them in a place where the wind blows MOST of the time, and it's not too slow for the windmills, and it's not too fast for them either.

That's a special kind of place.

There are a lot of places where the wind doesn't blow enough of the time, and when it does, it's either too slow or too fast for windmills to operate safely and efficiently. In places like that, you could spend a fortune to build windmills, but they wouldn't produce enough energy to make it worth the money.

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A tradesman sharpens a knife by pushing it with a constant force against the rim of a grindstone. The 30-cm-diameter stone is sp

Lorico [155]

Answer:

a. 0.21 rad/s2

b. 2.205 N

Explanation:

We convert from rpm to rad/s knowing that each revolution has 2π radians and each minute is 60 seconds

200 rpm = 200 * 2π / 60 = 21 rad/s

180 rpm = 180 * 2π / 60 = 18.85 rad/s

r = d/2 = 30cm / 2 = 15 cm = 0.15 m

a)So if the angular speed decreases steadily (at a constant rate) from 21 rad/s to 18.85 rad/s within 10s then the angular acceleration is

$\alpha = \frac{\Delta \omega}{\Delta t} = \frac{21 - 18.85}{10} = 0.21 rad/s^2$

b) Assume the grind stone is a solid disk, its moment of inertia is

$I = mR^2/2$

Where m = 28 kg is the disk mass and R = 0.15 m is the radius of the disk.

$I = 28*0.15^2/2 = 0.315 kgm^2$

So the friction torque is

$T_f = I\alpha = 0.315*0.21 = 0.06615 Nm$

The friction force is

$F_f = T_f/R = 0.06615 / 0.15 = 0.441 N$

Since the friction coefficient is 0.2, we can calculate the normal force that is used to press the knife against the stone

$N = F_f/\mu = 0.441/0.2 = 2.205 N$

7 0

3 years ago

Coulomb's law states that the force F of attraction between two oppositely charged particles varies jointly as the magnitude of

Mars2501 [29]

Answer: Force F will be one-sixteenth of the new force when the charges are doubled and distance halved

Explanation:

Let the charges be q1 and q2 and the distance between the charges be 'd'

Mathematical representation of coulombs law will be;

F1=kq1q2/d²...(1)

Where k is the electrostatic constant.

If q1 and q2 is doubled and the distance halved, we will have;

F2 = k(2q1)(2q2)/(d/2)²

F2 = 4kq1q2/(d²/4)

F2 = 16kq1q2/d²...(2)

Dividing equation 1 by 2

F1/F2 = kq1q2/d² ÷ 16kq1q2/d²

F1/F2 = kq1q2/d² × d²/16kq1q2

F1/F2 = 1/16

F1 = 1/16F2

This shows that the force F will be one-sixteenth of the new force when the charges are doubled and distance halved

4 0

3 years ago

What do you understand by ?efficiency of a machine is 70%

tatuchka [14]

Explanation:

The efficiency of a machine is 70% means 30% of the applied force is wasted in overcoming friction and 70% of the applied force is used to do the work

8 0

3 years ago

A flat loop of wire consisting of a single turn of cross-sectional area 8.00 cm2 is perpendicular to a magnetic field that incre

Evgen [1.6K]

Complete Question

A flat loop of wire consisting of a single turn of cross-sectional area 8.00 cm2 is perpendicular to a magnetic field that increases uniformly in magnitude from 0.500 T to 1.60 T in 0.99 s. What is the resulting induced current if the loop has a resistance of $1.20 \ \Omega$

Answer:

The current is $I = 0.0007 41 \ A$

Explanation:

From the question we are told that

The area is $A = 8.00 \ cm^2 = 8.0 *10^{-4} \ m^2$

The initial magnetic field at $t_o = 0 \ seconds$ is $B_i = 0.500 \ T$

The magnetic field at $t_1 = 0.99 \ seconds$ is $B_f = 1.60 \ T$

The resistance is $R = 1.20 \ \Omega$

Generally the induced emf is mathematically represented as

$\epsilon = A * \frac{B_f - B_i }{ t_f - t_o }$

=> $\epsilon = 8.0 *10^{-4} * \frac{1.60 - 0.500 }{ 0.99- 0 }$

=> $\epsilon = 0.000889 \ V$

Generally the current induced is mathematically represented as

$I = \frac{\epsilon}{R }$

=> $I = \frac{0.000889}{ 1.20 }$

=> $I = 0.0007 41 \ A$

6 0

3 years ago

Compare the numbers of protons and electrons in a positive ion with the numbers of protons and electrons in a negative ion.

kow [346]

Answer:

In a positive ion, the number of protons is larger than the number of electrons.

In a negative ion, the number of protons is smaller than the number of electrons.

Explanation:

Each proton carries a positive charge of one unit.

Each elec in tron carries a negative charge of one unit.

In an atom, there are as many protons as electrons. Hence, they are neutral.

However, in a positive ion, there are less negative charge than positive charge. Hence the net charge is positive. That also means that there are fewer negatively-charged electrons than positively-charged protons.

Similarly, in a negative ion, there are more negative charge than positive charge. Hence the net charge is negative. That also means that there are more negatively-charged electrons than positively-charged protons.

6 0

3 years ago