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3 years ago

A bus starts to move from rest. If its velocity becomes 90 km/hr after 8 seconds, calculate its acceleration.

Physics

1 answer:

a_sh-v [17]3 years ago

7 0

Answer:

The acceleration is 11.25 km/hr

Explanation:

Divide the velocity over time to find the acceleration. The bus is accelerating 11.25 km/hr per second in the range of 8 seconds

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__________ is/are formed between two air masses that have different temperatures. (4 points) A: Wind B:The jet stream C:Clouds D

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The answer is B: the jet stream.

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For each pair of vehicles, choose the vehicle that would experience the greatest force of impact in a collision. Type your answe

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3 years ago

An inverse-time circuit breaker (CB) is used for branch-circuit short-circuit and ground-fault protection for a 30-horsepower, 2

Maru [420]

Answer:

Explanation:

Motor rating is given in horsepower (hp), it will be converted in watt (W).

Standard to install circuit breaker for an electric circuit is usually 20% ~ 25% more than the Rated Current of the circuit

while

Standard to install overload relay for an electric circuit is usually 20% ~ 25% more than the Running Current of the circuit.

So, to find the maximum capacity of the circuit breaker, rated current of the motor will be multiplied by 1.2 ~ 1.25

Step by Step Explanation:

30hp = 22371W (as 1hp = 745.7)

Assuming unity power factor (cosФ=1) and 208V phase to phase voltage:

Rated Power (watt) = √3 . V.I. cosФ

{if 208V is phase to neutral voltage, then use following formula:

Rated Power (watt) = 3 . V.I. cosФ}

$\frac{22371}{\sqrt{3} * 208 * 1} = I$

Rated Current = 62.169A

So, required maximum rating for circuit breaker is:

20% to 25% of the rated current = 62.17*1.2 ~ 62.17*1.25

=74.6A ~ 77.7A

Hence, any breaker between the above mentioned rating will be appropriate.

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3 years ago

not all objects have a volume that is measured easily. If you were to determine the mass, volume, and density of your textbook,

Maslowich

Text book: We can measure the mass of the text book easily by weighing machine, to measure the volume we need to measure the length, width, and height of the text book by the ruler, by multiplying these dimension we can get the volume of the text book, and by dividing the mass of the book with its volume we can get the density of the book.

Milk Container: We can measure the mass of the milk container easily by weighing machine, now (assuming the milk container is cylindrical in shape) we need to measure its height, and and diameter and by the formula (π*r^2*h) we can measure its volume, and and by dividing the mass with its volume we can get the density of the milk container.

Air filled balloon: we can measure the mass of the air filled balloon by weighing it weight machine, we know that the density of air is 28.97 kg/m^3, by dividing the mass of the balloon with the denisty of air we can get the volume of the balloon.

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3 years ago

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A nonconducting spherical shell, with an inner radius of 4 cm and an outer radius of 6 cm, has charge spread non uniformly throu

Aloiza [94]

In other words a infinitesimal segment dV caries the charge
dQ = ρ dV 

Let dV be a spherical shell between between r and (r + dr): 
dV = (4π/3)·( (r + dr)² - r³ ) 
= (4π/3)·( r³ + 3·r²·dr + 3·r·(dr)² + /dr)³ - r³ ) 
= (4π/3)·( 3·r²·dr + 3·r·(dr)² + /dr)³ ) 
drop higher order terms 
= 4·π·r²·dr 

To get total charge integrate over the whole volume of your object, i.e. 
from ri to ra: 
Q = ∫ dQ = ∫ ρ dV 
= ∫ri→ra { (b/r)·4·π·r² } dr 
= ∫ri→ra { 4·π·b·r } dr 
= 2·π·b·( ra² - ri² ) 

With given parameters: 
Q = 2·π · 3µC/m²·( (6cm)² - (4cm)² ) 
= 2·π · 3×10⁻⁶C/m²·( (6×10⁻²m)² - (4×10⁻²m)² ) 
= 3.77×10⁻⁸C 
= 37.7nC

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3 years ago