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3 years ago

Once a satelite has entered a stable orbit round earth why does it not need fuel?

1 answer:

5 0

For the same reason that the Earth doesn't need any fuel to keep
orbiting the sun, and the moon doesn't need any fuel to keep
orbiting the Earth..

Here's something to think about: A satellite in a perfectly circular
orbit always stays at the same distance from the Earth, so it never
moves in the direction of the gravitational force. The work that
gravity does on it is (force) x (distance) = zero, so the satellite's
energy never changes.

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a 1600 kg car on flat ground is moving 6.25 m/s. its engine creates 1150 N forward force as the car moves 45.8 m. what is it fin

Sveta_85 [38]

Answer:

83,900 J

Explanation:

First, find the acceleration:

F = ma

1150 N = (1600 kg) a

a = 0.719 m/s²

Now find the final velocity.

Given:

Δx = 45.8 m

v₀ = 6.25 m/s

a = 0.719 m/s²

Find: v

v² = v₀² + 2aΔx

v² = (6.25 m/s)² + 2 (0.719 m/s²) (45.8 m)

v = 10.2 m/s

Now find the final KE:

KE = ½ mv²

KE = ½ (1600 kg) (10.2 m/s)²

KE = 83,920 J

Rounded to three significant figures, the final kinetic energy is 83,900 J.

6 0

3 years ago

A 74 kg firefighter slides, from rest, 4.9 m down a vertical pole. (a) If the firefighter holds onto the pole lightly, so that t

In-s [12.5K]

Answer:

Her speed is 9.8 meter per second

Explanation:

Newton's second law states that acceleration (a) is related with force (F) by:

$\sum\overrightarrow{F}=m\overrightarrow{a}$ (1)

Here the only force acting on the firefighter is the weight F=mg so (1) is:

$mg=ma$

Solving for a:

$a=g$

Now with the acceleration we can use the Galileo's kinematic equation:

$Vf^{2}=Vo^{2}+2a\varDelta x$ (2)

With Vf the final velocity, Vo the initial velocity and Δx the displacement, because the firefighter stars from rest Vo=0 so (2) is:

$Vf^{2}=2a\varDelta x$

Solving for Vf

$Vf=\sqrt{2g\varDelta x}=\sqrt{2(9.81)(4.9)}$

$Vf=9.8\frac{m}{s}$

6 0

2 years ago

Why would we expect protogalactic clouds with relatively high density to form an elliptical galaxy rather than a spiral galaxy?

Svetlanka [38]

The higher density allows the protogalactic clouds to cool faster and form an elliptical galaxy rather than a spiral galaxy.

In physical cosmology, a protogalaxy or protogalactic cloud , which could also be called a "primeval galaxy", is a cloud of gas which is forming into a galaxy. It is believed that the rate of star formation during this period of galactic evolution will determine whether a galaxy is a spiral or elliptical galaxy; a slower star formation tends to produce a spiral galaxy. The smaller clumps of gas in a protogalaxy form into stars.

Composition

Since there had been no previous star formation to create other elements, protogalaxies would have been made up almost entirely of hydrogen and helium. The hydrogen would bond to form H2 molecules, with some exceptions. This would change as star formation began and produced more elements through the process of nuclear fusion.

Mechanics

Once a protogalaxy begins to form, all particles bound by its gravity begin to free fall towards it. The time taken for this free-fall to conclude can be approximated using the free-fall equations. Most galaxies have completed this free-fall stage to become stable elliptical or disk galaxies, the disks taking longer to fully form. The formation of galaxy clusters takes much longer and is still in progress now.

This stage is also where galaxies acquire most of their angular momentum. A protogalaxy acquires this due to gravitational influence from neighbouring dense clumps in the early universe, and the further the gas is away from the centre, the more spin it gets.

Learn more about protogalactic clouds here : brainly.com/question/28166070

#SPJ4

7 0

1 year ago

A boy uses a force to keep a rock from falling. (He is carrying the rock.) Some forces, like this one, act only when two objects

MArishka [77]

Gravity is a non contact force , jump from a little high place (don't do that :P) , you wont just get stuck in the air you will fall down , this is gravity you dont need any contact

5 0

3 years ago

The Earths magnetic field deflects the flow of current from?

Zarrin [17]

<span>Most of the earth's fresh water is stored as ice in the Arctic and Antarctic regions of the globe.</span>

5 0

2 years ago