Unlike mechanical waves such as sound or earthquake waves, EM waves can travel through empty space. True or false

According to the Law of Conservation of Energy, why does the first hill on a roller coaster always have to be the tallest of all

enyata [817]

Because it generates enough momentum to keep the train going with out really having to speed up

5 0

3 years ago

A disk shaped grindstone of mass 3.0 kg and radius 8 cm is spinning at 600 rpm. After the power is shut off the frictional torqu

seropon [69]

Answer:

$\theta=50\ revolution$

Explanation:

It is given that,

Mass of the grindstone, m = 3 kg

Radius of the grindstone, r = 8 cm = 0.08 m

Initial speed of the grindstone, $\omega_i=600\ rpm=62.83\ rad/s$

Finally it shuts off, $\omega_f=0$

Time taken, t = 10 s

Let $\alpha$ is the angular acceleration of the grindstone. Using the formula of rotational kinematics as :

$\alpha =\dfrac{\omega_f-\omega_i}{t}$

$\alpha =\dfrac{0-62.83}{10}$

$\alpha =-6.283\ rad/s^2$

Let $\theta$ is the number of revolutions of the grindstone after the power is shut off. Now using the third equation of rotational kinematics as :

$\omega_f^2-\omega_i^2=2\alpha \theta$

$\theta=\dfrac{\omega_f^2-\omega_i^2}{2\alpha }$

$\theta=\dfrac{-62.83^2}{2\times -6.283}$

$\theta=314.15\ radian$

$\theta=49.99\ revolution$

or

$\theta=50\ revolution$

So, the number of revolutions of the grindstone after the power is shut off is 50.

7 0

3 years ago

3. An astronaut on a space-walk swings a 0.5 kg metal tool in a circular path at the end of a cable 3.6 m long. The astronaut th

Semenov [28]

Answer:

Explanation:

2 km a hour

6 0

3 years ago

Whats the force of gravitation of a 10kg rock and 100kg boulder which are 5 meters apart

spayn [35]

Answer:

F = 2.6692 x 10⁻⁹ N

Explanation:

Given,

The mass of the rock, m = 10 kg

The mass of the boulder, M = 100 kg

The distance between them, d = 5 m

The gravitational force between the two bodies is proportional to the product of their masses and inversely proportional to the square of the distance between them. It is given by the formula

<em> F = GMm/d² newton</em>

Where,

G - Universal gravitational constant

Substituting the given values,

F = 6.673 x 10⁻¹¹ x 100 x 10 / 5²

F = 2.6692 X 10⁻⁹ N

Hence, the force between the two bodies is, F = 2.6692 X 10⁻⁹ N

6 0

3 years ago

Which strategy should you use if your research question is too broad for the scope of your project? (1 O narrow the focus of res

Nesterboy [21]

Answer:

"Narrow the focus of research question"

Explanation:

O Narrow the focus of research question

This is good! You can still use your question, but focus in on something so you have a proper research project.

O Add another research question

Would adding another question to an already broad question help? No.

O Use the very first source you find for your project

If your question is too broad, you should not use whatever you see first as it may be incorrect or does not answer the question

O Change the scope of your project

You could, but if you have a set scope for your project (a) you might not be able to change it (b) you don't need to restart

Have a nice day!

I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly. (ノ^∇^)

- Heather

3 0

2 years ago