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3 years ago

5

You need to know the height of a tower, but darkness obscures the ceiling. You note that a pendulum extending from the ceiling a

lmost touches the floor and that its period is 23 s. The acceleration of gravity is 9.81 m/s 2 . How tall is the tower? Answer in units of m

1 answer:

Elis [28]3 years ago

4 0

Answer:

131.3 m

Explanation:

Period of pendulum depends on the length of the pendulum. It can be calculated by using the formula:

$T=2\pi\sqrt{\frac{l}{g}}$

$23s=2\pi\sqrt\frac{l}{9.81}\\\Rightarrow 3.66\times 3.13=\sqrt{l}\\\Rightarrow \sqrt l=11.46 \\ \Rightarrow l = 131.3 m$

Thus, tower is 131.3 m tall.

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When a 20-V emf is placed across two resistors in series, a current of 2.0 A is present in each of the resistors. When the same

ehidna [41]

Answer:

7.24 ohm

Explanation:

Let R1 and R2 are resistance of two resistors.

Emf=E=20 V

Current,I=2 A

Current,I'=10 A

We have to find the magnitude of the greater of the two resistances.

In series

$R=R_1+R_2$

$V=IR$

By using the formula

$20=2(R_1+R_2)$

$R_1+R_2=\frac{20}{2}=10$ ...(1)

In parallel

$\frac{1}{R}=\frac{1}{R_1}+\frac{1}{R_2}$

$\frac{1}{R}=\frac{R_2+R_1}{R_1R_2}$

$R=\frac{R_1R_2}{R_1+R_2}$

$20=10(\frac{R_1R_2}{R_1+R_2}$

$2=\frac{R_1R_2}{10}$

$R_1R_2=20$

$R_2=\frac{20}{R_1}$

Substitute the value

$\frac{20}{R_1}+R_1=10$

$R^2_1+20=10R_1$

$R^2_1-10R_1+20=0$

$R_1=\frac{10\pm\sqrt{(-10)^2-4(20)}}{2}$

By using quadratic formula

$x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$

$R_1=\frac{10\pm 2\sqrt 5}{2}$

$R_1=\frac{10+2\sqrt 5}{2}=5+\sqrt 5=7.24 ohm$

$R_1=\frac{10-2\sqrt 5}{2}=2.76 ohm$

Substitute the value

$R_2=\frac{20}{7.24}=2.76 ohm$

$R_2=\frac{20}{2.76}=7.24 ohm$

Hence, the magnitude of the greater of the two resistance=7.24 ohm

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3 years ago

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A straight 1.20 m long conductor has a 2.00 A current travelling toward the East. Earth's magnetic field in this location is 4.9

KATRIN_1 [288]

Answer:

Force's magnitude $=1.176\,10^{-4}\,N$

Direction: down (towards the center of the Earth)

Explanation:

Recall that the magnetic force on a conductor of length L carrying a current I in a magnetic field B is given by the equation: $F=I\,L\,B$ in the case the magnetic field B and the direction of the current are at 90 degrees from each other (which is our case). The direction of the force will be given by the "right hand rule" associated with the vector product that defines this force.

Since the current is moving East, and the magnetic field of the Earth goes from North to South, the resultant Force vector will be pointing towards the Earth (and perpendicular to the plane defined by the current's direction and the magnetic field B)

The magnitude of the force, is given by the formula above, and given that all quantities to be considered are is SI units, it will result in Newtons (N):

$F=I\,L\,B\\F=2\,*\,1.2\,*\,4.9\,10^{-5}\,N\\F=1.176\,10^{-4}\,N$

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4 years ago

Which magnetic property best describes a magnet’s ability to act at a distance?

blsea [12.9K]

Magnetic field describea magnet's ability to act at a distance

8 0

4 years ago

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What is the equation for finding the amount of inertia in forces and motion? Explain how you solve that equation.

jolli1 [7]

Answer:

Inertia = angular momentum / angular velocity

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2 years ago

A hummingbird flies forward and backward. Its motion is shown on the above graph of horizontal Position and

harina [27]

Answer:

The hummingbird travels the total distance is 10 m

Explanation:

Given that,

A hummingbird flies forward and backward.

According to figure,

We know that,

The total distance is equal to the sum of all distance.

Forward direction is positive and backward direction is negative.

We need to calculate the hummingbird travels the total distance

Using figure,

$D=d_{1}+d_{2}+d_{3}+d_{4}$

Put the value into the formula

$D=6+(-4)+2+6$

$D=10\ m$

Hence, The hummingbird travels the total distance is 10 m.

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4 years ago