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2 years ago

A student hears a police siren. What would change the frequency that the student hears? Check all that apply.

Physics

2 answers:

BlackZzzverrR [31]2 years ago

9 0

Answer:

Explanation:

It's right on Edge

ser-zykov [4K]2 years ago

4 0

<span>A student hears a police siren.

The arithmetic of the Doppler Effect shows that if the distance between
the source and observer is changing, then the observer hears a different
frequency compared to the frequency actually radiating from the source.

Thus the first four choices would cause the student to hear a different
frequency:

-- if the student walked toward the police car
-- if the student walked away from the police car
-- if the police car moved toward the student
-- if the police car moved away from the student

The last two choices wouldn't affect the frequency heard by the student,
since the perceived frequency of a sound doesn't depend on its intensity.

-- if the intensity of the siren increased
-- if the intensity of the siren decreased.</span>

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sveta [45]

Answer:

A) B = 9.425 × 10^(-5) T

B) North direction

Explanation:

A) We are given;

Current in coil; I = 4.5 A

Number of turns; N = 100 turns

Radius;R = diameter/2 = 6/2 = 3 m

Formula for the magnetic field at the center of the coil is given by;

B = (μ_o•N•I)/2R

Where μ_o is a constant = 4π × 10^(-7) H/m

Thus;

B = (4π × 10^(-7) × 100 × 4.5)/(2 × 3)

B = 9.425 × 10^(-5) T

B) The direction of the force on a positive ion in water can be gotten by the application of flemmings right hand rule.

From flemmings right hand rule, we know that;

- The thumb indicates the direction of the motion of the force which is in the north direction.

- The Index finger indicates the direction of the magnetic field which is in the east direction

- The middle finger indicates the direction of magnetic field which is downwards in the west direction.

Therefore, the direction of the force as seen from flemmings right hand rule is in the north direction

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2 years ago

Two very large parallel metal plates, separated by 0.20 m, are connected across a 12-V source of potential. An electron is relea

Semmy [17]

Answer:

${\rm K} = 2.4\times 10^{-19}~J$

Explanation:

The electric field inside a parallel plate capacitor is

$E = \frac{Q}{2\epsilon_0 A}$

where A is the area of one of the plates, and Q is the charge on the capacitor.

The electric force on the electron is

$F = qE = \frac{qQ}{2\epsilon_0 A}$

where q is the charge of the electron.

By definition the capacitance of the capacitor is given by

$C = \epsilon_0\frac{A}{d} = \frac{Q}{V}\\\frac{Q}{\epsilon_0 A} = \frac{V}{d} = \frac{12}{0.20} = 60$

Plugging this identity into the force equation above gives

$F = \frac{qQ}{2\epsilon_0 A} = \frac{q}{2}(\frac{Q}{\epsilon_0 A}) = \frac{q}{2}60 = 30q$

The work done by this force is equal to change in kinetic energy.

W = Fx = (30q)(0.05) = 1.5q = K

The charge of the electron is $1.6 \times 10^{-19}$

Therefore, the kinetic energy is $2.4\times 10^{-19}$

8 0

2 years ago

A wire has an electric field of 6.2 V/m and carries a current density of 2.4 x 108 A/m2. What is its resistivity

ZanzabumX [31]

Answer:

The resistivity is $\rho = 2.5 *10^{-8} \ \Omega \cdot m$

Explanation:

From the question we are told that

The magnitude of the electric field is $E = 6.2 V/m$

The current density is $J = 2.4 *10^{8} \ A/m^2$

Generally the resistivity is mathematically represented as

$\rho = \frac{E}{J}$

substituting values

$\rho = \frac{6.2}{2.4 *10^{8}}$

$\rho = 2.5 *10^{-8} \ \Omega \cdot m$

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2 years ago

Some plants disperse their seeds when the fruit splits and contracts, propelling the seeds through the air. The trajectory of th

Anton [14]

Answer:

Option B, 93 cm

Explanation:

An diagram of the seed's motion is attached to this solution.

This is very close to a projectile motion question. And the quantity to be calculated, how far along the grant a seed released would travel is called the Range.

And this would be obtained from the equations of motion,

First of, the height of the plant is related to some quantities of the motion with this relation.

H = u(y) t + 0.5g(t^2)

U(y) = initial vertical component of velocity = 0 m/s, H = height at which motion began, = 20cm = 0.2 m

That means t = √(2H/g)

The horizontal distance covered, R,

R = u(x) t + 0.5g(t^2) = u(x) t (the second part of the equation goes to zero as the vertical component of the acceleration of this motion is 0)

(substituting the t = √(2H/g) derived from above

R = u(x) √(2H/g)

Where u(x) = the initial horizontal component of the bomb's velocity = maximum initial speed, that is, 4.6 m/s, H = vertical height at which the seed was released = 20 cm = 0.2 m, g = acceleration due to gravity = 9.8 m/s2

R = 4.6 √(2×0.2/9.8) = 0.929 m = 0.93 m = 93 cm. Option B.

QED!