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sweet [91]
3 years ago
10

The highest free-standing tower in North America is the CN Tower in Toronto, Canada. From a distance of 1km from its base, the a

ngle of elevation to the top of the tower is 28.81 degrees. Find the height of the tower, rounded to two decimal places.
Physics
1 answer:
Whitepunk [10]3 years ago
4 0
The height of the tower and the distance from its base form a right angle triangle. Thus,
tan(∅) = height / base
tan(28.81) = height / 1,000 m
height = 549.98 meters
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An uncharged series RC circuit is to be connected across a battery. For each of the following changes, determine whether the tim
slavikrds [6]

a) Increase

b) Unchanged

c) Increase

Explanation:

a)

The charge on a capacitor charging in a RC circuit connected to a battery follows the exponential equation:

Q(t)=Q_0 (1-e^{-\frac{t}{RC}})

where

Q_0 = CV is the final charge stored in the capacitor, where C is the capacitance and V is the voltage of the battery

t is the time

R is the resistance of the circuit

The capacitor reaches 90% of its final charge when

Q(t)=0.90Q_0

Substituting and re-arranging the equation, we find:

0.90Q_0 = Q_0(1-e^{-\frac{t}{RC}})\\0.90=1-e^{-\frac{t}{RC}}\\e^{-\frac{t}{RC}}=0.10\\-\frac{t}{RC}=ln(0.10)\\t=-RCln(0.10)=2.30RC

We see that if we double the RC constant, then (RC)'=2(RC)

So the time taken will double as well:

t'=2.30(RC)'=2.30(2RC)=2(2.30RC)=2t

So, the answer is "increase"

b)

In this second part, the battery voltage is doubled.

According to the equation written in part a),

Q_0 =CV

this means also that the final charge stored on the capacitor will also double.

However, the equation that gives us the time needed for the capacitor to reach 90% of its full charge is

t=2.30 RC

We see that this equation does not depend at all on the voltage of the battery.

Therefore, if the battery voltage is doubled, the final charge on the capacitor will double as well, but the time needed for the capacitor to reach 90% of its charge will not change.

So the correct answer is

"unchanged"

c)

In this case, a second resistor is added in series with the original resistor of the circuit.

We know that for two resistors in series, the total resistance of the circuit is given by the sum of the individual resistances:

R=R_1+R_2

Since each resistance is a positive value, this means that as we add new resistors, the total resistance of the circuit increases.

Therefore in this problem, if we add a resistor in series to the original circuit, this means that the total resistance of the circuit will increase.

The time taken for the capacitor to reach 90% of its final charge is still

t=2.30 RC

As we can see, this time is directly proportional to the resistance of the circuit, R: therefore, if we add a resistor in series, the resistance of the circuit will increase, and therefore this time will increase as well.

So the correct answer is

"increase"

8 0
3 years ago
Energy in motion is _____ energy. potential scientific kinetic
Ket [755]

Answer:

kinetic energy

Explanation:

4 0
3 years ago
Read 2 more answers
"The drawing shows three layers of different materials, with air above and below the layers. The interfaces between the layers a
My name is Ann [436]

Answer:

Angle of incidence that entered material b= 63.1°

Angle of incidence between a and b = 55.9°

Explanation: Using the formular:

n1sintheta1= n2sintheta2

The light ray which enters material B will be

1.4Sin72.8° = 1.5Sin theta

1.3373= 1.5Sintheta

sintheta = 1.3373/1.5

Sin^-1 0.8916 = Theta

63.1 = theta

When the ray hits interface with material a

1.5Sin63.1 = 1.3 Sin theta

1.3374 = 1.3Sin theta

Sintheta= 1.3374/1.3

Sin theta = 1.0877

There will be total reflection off the boundary b c because sin theta exceeded 1 in value.

The equation should be

1.4sin63.1 = 1.4 sin theta

Sin theta=72.8°

When the ray hits air-c boundary:

1.4sin72.8=1.00sin theta

Sin theta=1.3374/1 =1.3374

There is total reflection.

In material a,the ray will:

1.3sin72.8° = 1.00sin theta

There will be total reflection when the ray hits a-b boundary.

1.3sin72.8= 1.5sintheta

Sin theta= 1.2419/ 1.5

Sin theta =0.8279

Theta= Sin^-10.8279= 55.88°

When ray hits c-air boundary

1.4sin63.1= 1.00sintheta

1.2485= sin theta = Toal reflection.

Therefore when the ray of light pass through the layers of material a, b and c the boundary with air on top and bottom will be total reflection.

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The water level rises, because ice is made of water
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vesna_86 [32]
It means that you consider the elements as a list organized by atomic number, the property is seen to repeat over and over as you move through that list.
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3 years ago
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