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nikdorinn [45]
3 years ago
13

Little is known about much of earth’s early history because ____.

Physics
2 answers:
algol [13]3 years ago
8 0

the answer is D) all of the above

denis23 [38]3 years ago
7 0
The correct answer is D
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Analyze the explanation and identify any false statements. Each statement to be analyzed is identified by a capital letter. A ba
Sladkaya [172]

Answer:

Explanation:

The rotational kinetic energy remains constant as long as the length and angular speed are fixed.

Statement A is true.

When the ball is pulled inward and the length of the string is shortened, the rotational kinetic energy will remain constant due to conservation of energy,

Statement B is false .

Reason - Conservation of energy will not be there because external work is done on the system  by the force that pulls it inward.  

but the angular momentum L will not remain constant because there is an external force acting on the ball to pull it inward

Statement C is false .

Reason - the angular momentum L will remain constant because there is an external force acting on the ball which acts perpendicular to the velocity of the ball .

The moment of inertia I remains constant

Statement D is false

Reason - because distance from axis of rotation is changing.

the angular speed will remain the same throughout the process because the ball is rotating in the same plane throughout the motion.

Statement E is false

Reason - Since moment of inertia decreases , to conserve angular momentum , angular speed increases.

4 0
2 years ago
The start-up procedure for a batch reactor includes a heating step where the reactor temperature is gradually heated to the nomi
qwelly [4]
Solution: 
f ( t )= 20 S ( t ) + 55/30 tS ( t )− 55/30 ( t − 30 ) S ( t − 30 ) 
• Taking the Laplace Transform: 
F ( s ) = 20/s + 55/30 ( 1/s^2 ) – 55/30 ( 1/s^2) e^-30s = 20/s + 55/30 ( 1/s^2 ) ( 1 – e^-30s) 

7 0
3 years ago
The speed of sound in water is 1,492 m/s. A sonar signal is sent straight down from a ship at a point just below the water's sur
ASHA 777 [7]

Answer:

5595 m

Explanation:

The wave travels down   (the depth) and the back up (the depth again)

  this distance is     2 d

2 d =  1492 m/s * 7.5 s

2d = 11190 m

d = 5595 m

6 0
1 year ago
True or false elliptical galaxies are made up of old stars containing small amount of gas
ch4aika [34]
True, They contain old stars and posses little gas or dust
6 0
3 years ago
A 70.0 kg astronaut is training for accelerations that he will experience upon reentry. He is placed in a centrifuge (r = 15.0 m
Levart [38]

Answer:

1.3823 rad/s

20.7345 m/s

28.66129935 m/s²

a=2.92164g

2006.29095 N radially outward

Explanation:

r = Radius = 15 m

m = Mass of person = 70 kg

g = Acceleration due to gravity = 9.81 m/s²

Angular velocity is given by

\omega=13.2\times \dfrac{2\pi}{60}\\\Rightarrow \omega=1.3823\ rad/s

Angular velocity is 1.3823 rad/s

Linear velocity is given by

v=r\omega\\\Rightarrow v=15\times 1.3823\\\Rightarrow v=20.7345\ m/s

The linear velocity is 20.7345 m/s

Centripetal acceleration is given by

a_c=r\omega^2\\\Rightarrow a_c=15\times 1.3823^2\\\Rightarrow a_c=28.66129935\ m/s^2

The centripetal acceleration is 28.66129935 m/s²

Acceleration in terms of g

\dfrac{a}{g}=\dfrac{28.66129935}{9.81}\\\Rightarrow a=2.92164g

a=2.92164g

Centripetal force is given by

F_c=ma_c\\\Rightarrow F_c=70\times 28.66129935\\\Rightarrow F_c=2006.29095\ N

The centripetal force is 2006.29095 N radially outward

The torque will be experienced when the centrifuge is speeding up of slowing down i.e., when it is accelerating and decelerating.

3 0
3 years ago
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