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Andrew [12]
3 years ago
15

A source emits sound uniformly in all directions. There are no reflections of the sound. At a distance of 12 m from the source,

the intensity of the sound is 3.5 × 10-3 W/m2. What is the total sound power P emitted by the source?
Physics
1 answer:
yaroslaw [1]3 years ago
7 0

Answer:

1.58 W

Explanation:

Since the sound spreads uniformly in all directions, it must be in a form of a circle with radius of 12 m. So the area of the circle is

A = \pi r^2 = \pi 12^2 = 452.389 m^2

From the intensity of the sound we can calculate the power at 12 m

P = AI = 452.389 * 3.5\times10^{-3} = 1.58 W

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Kazeer [188]
I'm pretty sure its a scale.
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3 years ago
A person slaps her leg with her hand, which results in her hand coming to rest in a time interval of 2.65 ms from an initial spe
dezoksy [38]

Answer:

the magnitude of the average contact force exerted on the leg is  3466.98 N

Explanation:

Given the data in the question;

Initial velocity of hand v₀ = 5.25 m/s

final velocity of hand v = 0 m/s

time interval t = 2.65 ms = 0.00265 s

mass of hand m = 1.75 kg

We calculate force on the hand F_{hand

using equation for impulse in momentum

F_{hand × t = m( v - v₀ )

we substitute

F_{hand × 0.00265  = 1.75( 0 - 5.25 )

F_{hand × 0.00265  = 1.75( - 5.25 )

F_{hand × 0.00265  = -9.1875

F_{hand = -9.1875 / 0.00265  

F_{hand = -3466.98 N

Next we determine force on the leg F_{leg

Using Newton's third law of motion

for every action, there is an equal opposite reaction;

so, F_{leg = - F_{hand

we substitute

F_{leg = - ( -3466.98 N )

F_{leg = 3466.98 N

Therefore, the magnitude of the average contact force exerted on the leg is  3466.98 N

5 0
2 years ago
[30 POINTS] An automobile steering wheel is shown. The ideal mechanical advantage of this wheel and axle = _____ .
mamaluj [8]

Rw/Ra = MA

18cm/2cm= MA

MA = 9

This means that Fi is 1/9 of the force applied to the axil. The distance travelled by Rw is 9 times more than Ri  is that you move 9 times more when turning the wheel using Rw.

Put more simply

Rw/Ra = Fa/Fw

  • Rw = Radius of the wheel
  • Ra = Radius of the axil
  • Fa = Force delivered on the axil
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7 0
2 years ago
An object moves in a straight path. Its position x as a function of time t is presented by the equation x(t) = at – bt2+c, where
ankoles [38]

Answer:

The answer is below

Explanation:

Given that:

x(t) = at – bt2+c

a) x(t) = at – bt2+c

Substituting a = 1.4 m/s, b = 0.06 m/s2 and c =50 m gives:

x(t) = 1.4t - 0.06t² + 50

At t = 5, x(5) = 1.4(5) - 0.06(5)² + 50 = 55.5 m

At t = 0, x(0) = 1.4(0) - 0.06(0)² + 50 = 50 m

The average velocity (v) is given as:

v=\frac{x(5)-x(0)}{5-0}\\ \\v=\frac{55.5-50}{5-0}=1.1\\ \\v=1.1\ m/s

b) x(t) = 1.4t - 0.06t² + 50

At t = 10, x(10) = 1.4(10) - 0.06(10)² + 50 = 58 m

At t = 0, x(0) = 1.4(0) - 0.06(0)² + 50 = 50 m

The average velocity (v) is given as:

v=\frac{x(10)-x(0)}{10-0}\\ \\v=\frac{58-50}{10-0}=0.8\\ \\v=0.8\ m/s

c) x(t) = 1.4t - 0.06t² + 50

At t = 15, x(5) = 1.4(15) - 0.06(15)² + 50 = 57.5 m

At t = 10, x(10) = 1.4(10) - 0.06(10)² + 50 = 58 m

The average velocity (v) is given as:

v=\frac{x(15)-x(10)}{15-10}\\ \\v=\frac{57.5-58}{15-10}=0.1\\ \\v=0.1\ m/s

6 0
3 years ago
Two lab carts are pushed together with a spring mechanism compressed between them. Upon release, the 5.0 kg cart repels one way
JulijaS [17]

Answer:

V = -0.3 m/sec.

Explanation:

5.0 x 0.12 + 2.0 x v = 0. Which means that V = -0.3 m/sec.

The -ve sign shows it moves in the opposite direction.

8 0
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