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marysya [2.9K]
3 years ago
13

a pillow , a textbook and a paper airplane are dropped from the top of a tall building at the same time. consider what you have

learned about air resistance . which object reaches the ground first ?
Physics
2 answers:
vaieri [72.5K]3 years ago
6 0
The textbook because it’s really heavy
MAVERICK [17]3 years ago
3 0

A textbook would hit the ground first


Factors:

-Textbook weighs most

-Pillow is flat and fluffy not very aerodynamic) also is very light

-Paper airplane will glide to the ground do to its wings and will hit the ground last

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The Milky Way is often considered to be an intermediately wound, barred spiral, which would be type ________ according to Hubble
barxatty [35]

Answer: SBb

On 1930 the astronomer Edwin Hubble classified the galaxies based on their visual appearance into elliptical, spiral and irregular, being the first two classes the most frequent.  

So, according to this classification, the Milky Way is a barred spiral galaxy (SBb in Hubble's notation system) because it has a central bar-shaped structure of bright stars that spans from one side of the galaxy to the other. In addition, its spiral arms seem to emerge from the end of this "bar".

Scientifics considered this, after measuring the the disk and central bulge region of the galaxy, and the conclusion is the Milky Way fulfills these conditions, because is a galaxy that orbits on its same axis and with this rotation its arms are twisted in opposite directions around the mentioned axis.

7 0
4 years ago
(II) A 20.0-kg box rests on a table. (a) What is the weight of the box and the normal force acting on it? (b) A 10.0-kg box is p
Bogdan [553]

*Fig is Attached with answer*

Answer:

(a)   Weight = Normal Force = 196.2 N

(b)   Normal force table on 20 kg box = 294.3 N

       Normal force 20 kg box on 10 kg box = 98.1 N

Explanation:

(a)   Mass = m = 20 kg                           g = 9.81 m/s²

      Weight = w = mg

                      w = 20 × 9.81

                      w = 196.2 N

As the box rests on the table so, normal force (NF) must be equal to the weight of the box.

                    NF = w = 196.2 N

(b)

m₁ = 20 kg                      m₂ = 10 kg

total mass = M = 30 kg

Total Weight = W = Mg  

                             = 30 × 9.81

                             = 294.3 N

As both the boxes rest on the table so, normal force (NF) must be equal to the total weight of the boxes.

                          NF = W = 294.3 N

Weight of 10 kg box = 10 × 9.81 = 98.1 N

As the 10 kg box is placed on the top of 20 kg box, So 20 kg box must exert a normal force that is equal to the weight of 10 kg box.

              Normal Force = Weight of 10 kg box = 98.1 N

6 0
3 years ago
Contrast the average speed and the instantaneous speed of runner in a race.
ehidna [41]

Average speed of the runner is the rate at which the runner covers the total distance. Average speed of the runner in the race is given by,

Average speed = \frac{Total distance}{Total time}

Where

Total distance = Distance covered by the runner from initial to final position

Total time = time taken by the runner to cover entire distance

Instantaneous speed is the speed of the runner at the particular moment in the given time. Instantaneous speed is given by,

Instantaneous speed = \frac{dx}{dt}

x = position of the runner at time t

t = time taken to cover distance x

Hence, Average speed and instantaneous speed are different for a runner running in the race.


6 0
3 years ago
On February 15, 2013, a superbolide meteor (brighter than the Sun) entered Earth's atmosphere over Chelyabinsk, Russia, and expl
fredd [130]

Answer:

156.67 m/s

0.45676 times the speed of sound

Explanation:

Distance from the ground = 23.5 km = 23500 m

Time taken by the blast waves to reach the ground = 2\ minutes\ 30\ seconds=2\times 60+30=150\ s

Spedd of the wave would be

Speed=\dfrac{Distance}{Time}\\\Rightarrow v_b=\dfrac{23500}{150}\\\Rightarrow v-b=156.67\ m/s

The velocity of the blast wave is 156.67 m/s

v = Velocity of sound = 343 m/s

\dfrac{v_b}{v}=\dfrac{156.67}{343}\\\Rightarrow v_b=v\dfrac{156.67}{343}\\\Rightarrow v_b=0.45676v

The blast wave is 0.45676 times the speed of sound

7 0
4 years ago
Help!! <br> A. 0.5 s <br> B. 1.0 s<br> C. 1.5 s<br> D. 2.0 s
algol13

Answer:

c.    1.5 s

Explanation:

i had this and i got it right

3 0
3 years ago
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