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4 years ago

What makes the north star, polaris, special?

1 answer:

7 0

It's the only star in the sky (visible from the northern hemisphere) that never seems to move. It stays at almost exactly the same point in the sky, while the other stars all circle around it once a day.

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What name is given to the turning effect of a force?

Alex787 [66]

Answer:

The turning effect of a force is known as the moment. It is the product of the force multiplied by the perpendicular distance from the line of action of the force to the pivot or point where the object will turn. When undoing a nut fastened to a screw by hand one realises that the amount of force required is a lot greater than when undoing the same nut using a spanner.

Explanation:

6 0

3 years ago

A stone is dropped into a river from a bridge at a height h above the water. Another stone is thrown vertically down at a time t

Mumz [18]

Answer:

$v_{y_0} = \frac{\frac{g}{2}t(t - 2\sqrt{\frac{2h}{g}})}{\sqrt{\frac{2h}{g}} - t}$

Explanation:

We will apply the equations of kinematics to both stones separately.

First stone:

Let us denote the time spent after the second stone is thrown as 'T'.

$y - y_0 = v_{y_0}(t+T) + \frac{1}{2}a(t+T)^2\\0 - h = 0 + \frac{1}{2}(-g)(t+T)^2\\(t+T)^2 = \frac{2h}{g}\\T = \sqrt{\frac{2h}{g}}-t$

Second stone:

$y - y_0 = v_{y_0}T + \frac{1}{2}aT^2\\0 - h = v_{y_0}T -\frac{1}{2}gT^2\\-h = v_{y_0}(\sqrt{\frac{2h}{g}} - t) - \frac{g}{2}(\sqrt{\frac{2h}{g}} - t)^2\\-h = v_{y_0}(\sqrt{\frac{2h}{g}} - t) - \frac{g}{2}(\frac{2h}{g} + t^2 - 2t\sqrt{\frac{2h}{g}})\\-h = v_{y_0}\sqrt{\frac{2h}{g}} - v_{y_0}t - h -\frac{g}{2}t^2 + gt\sqrt{\frac{2h}{g}}\\v_{y_0}(\sqrt{\frac{2h}{g}} - t) = \frac{g}{2}t^2 - gt\sqrt{\frac{2h}{g}}\\v_{y_0} = \frac{\frac{g}{2}t(t - 2\sqrt{\frac{2h}{g}})}{\sqrt{\frac{2h}{g}} - t}$

6 0

3 years ago

Read 2 more answers

Nếu tăng khoảng cách giữa hai điểm lên 4 lần thì lực tương tác tĩnh điện giữa chúng sẽ

ohaa [14]

Answer:

điện giữa chúng s

Explanation:

8 0

3 years ago

A ship is to reach a place 10° south of west. In what direction should it be steered if declination at the place is 17° west?.

Readme [11.4K]

The direction is 7⁰ from west to the south.

We need to know about the degree and direction to solve this problem. The angle between west and south is 90⁰.

From the question above, we know that

Position = 10⁰ south of west

Destination = 17⁰ south of west

Hence, the direction of the ship should be

Direction from west = Destination - Position

Direction from west = 17⁰ - 10⁰

Direction from west = 7⁰

The direction is 7⁰ from west

Direction from south = Destination - Position

Direction from south = (90⁰ - 17⁰) - (90⁰ - 10⁰)

Direction from south = -7⁰

The direction is 7⁰ to the south.

Hence, the direction is 7⁰ from west to the south.

For more on directions at: brainly.com/question/6559935

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6 0

2 years ago

Use the second laws of thermodynamics to explain how an incandescent bulb might be less efficient than a compact fluorescent bul

Vsevolod [243]

An incandescent bulb produces light that comes from the heating of a filament. A compact fluorescent bulb produces light when a substance is hit by electromagnetic radiation. Compact fluorescent bulbs are more efficient than incandescent bulbs.

The first law of thermodynamics is a version of the law of conservation of energy, adapted for thermodynamic processes. Therefore, a system with lower heat emissions would be more efficient.

The second law of thermodynamics states that the total entropy of an isolated system (the thermal energy per unit temperature that is unavailable for doing useful work) can never decrease. In our context, it means that the system with the least amount of losses would be more efficient. As a conclusion the fluorescent bulb would be more efficient.

8 0

2 years ago