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Setler [38]
2 years ago
5

"Fifteen hundred years ago everybody knew the Earth was the center of the universe. Five hundred years ago, everybody knew the E

arth was flat, and fifteen minutes ago, you knew that humans were alone on this planet. Imagine what you’ll know tomorrow.” That's a statement of Agent Kay in from Men in Black. Agent Kay's statement illustrates that theories are A) always true. B) constantly changing. C) describe what happens in the natural world. D) are proven by evidence collected by scientists.
Physics
2 answers:
Elenna [48]2 years ago
7 0
I believe its B, constantly changing
Furkat [3]2 years ago
6 0

Scientific theories are constantly changing for many reasons. Sometimes it IS because of new evidence. But we would not use the term proven because they ARE always changing! Therefore, the answer is B.

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Technician A says that shop air pressure usually ranges from 100–150 psi. Technician B says shop air pressure is around 300 psi.
mr Goodwill [35]

Answer:

technician A.

Explanation:

Commonly,  air pressure rating of standard shop air compressor's is between the range of 100 psi and 150 psi. And over the years since, the plant pressure creep's up , the level of pressure increases from 100 psi to at max 150 psi but not more than that. Therefore, in the given question technician A is correct and technician B is incorrect.

5 0
2 years ago
Your friend thinks that the escape speed should be greater for more massive objects than for less massive objects. Provide an ar
Brrunno [24]

Answer:

Concepts and Principles

1- Kinetic Energy: The kinetic energy of an object is:

K=1/2*m*v^2                                                         (1)  

where m is the object's mass and v is its speed relative to the chosen coordinate system.  

2- Gravitational potential energy of a system consisting of Earth and any object is:  

 U_g = -Gm_E*m_o/r*E-o                                   (2)  

where m_E is the mass of Earth (5.97x 10^24 kg), m_o is the mass of the object, and G = 6.67 x 10^-11 N m^2/kg^2 is Newton's gravitational constant.  

Solution  

The argument:  

My friend thinks that escape speed should be greater for more massive objects than for less massive objects because the gravitational pull on a more massive object is greater than the gravitational pull for a less massive object and therefore the more massive object needs more speed to escape this gravitational pull.  

The counterargument:  

We provide a mathematical counterargument. Consider a projectile of mass m, leaving the surface of a planet with escape speed v. The projectile has a kinetic energy K given by Equation (1):

K=1/2*m*v^2                                                         (1)  

and a gravitational potential energy Ug given by Equation (2):  

Ug = -G*Mm/R

where M is the mass of the planet and R is its radius. When the projectile reaches infinity, it stops and thus has no kinetic energy. It also has no potential energy because an infinite separation between two bodies is our zero-potential-energy configuration. Therefore, its total energy at infinity is zero. Applying the principle of energy consersation, we see that the total energy at the planet's surface must also have been zero:  

K+U=0  

1/2*m*v^2 + (-G*Mm/R) = 0

1/2*m*v^2 =  G*Mm/R

1/2*v^2 = G*M/R

solving for v we get

v = √2G*M/R

so we see v does not depend on the mass of the projectile

8 0
3 years ago
What type of device is a car engine?
rusak2 [61]

heat engine that uses work to move heat

mark brainliest  :)

7 0
3 years ago
Free fall is a situation in which the only force acting upon an object is gravity. Why do all objects in free fall have the same
Angelina_Jolie [31]

free fall is a special type of motion in which the only force acting upon an object is gravity.  all objects will fall with the same rate of acceleration, regardless of their mass.

5 0
3 years ago
Read 2 more answers
Huck Finn walks at a speed of 0.70 m/sm/s across his raft (that is, he walks perpendicular to the raft's motion relative to the
exis [7]

Answer:

Explanation:

Given

Velocity of Huck w.r.t to raft v_{H,raft}=0.7\ m/s

Perpendicular to the motion of raft

Velocity of Raft in the river v_{raft,river}=1.6\ m/s

As Huck is traveling Perpendicular to the raft so he possess two velocities i.e. vertical velocity and horizontal velocity of River when observed from bank

v_{Huck,river\ bank}=0.7\hat{j}+1.6\hat{i}

So magnitude of velocity is given by

|v|=\sqrt{0.7^2+1.6^2}

|v|=\sqrt{0.49+2.56}

|v|=\sqrt{3.05}

|v|=1.74\ m/s

For direction \tan =\frac{0.7}{1.6}=0.4375

\theta =23.63^{\circ} w.r.t river bank

                       

4 0
2 years ago
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