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disa [49]
3 years ago
13

A motorcycle and a police car are moving toward one another. The police car emits sound with a frequency of 523 Hz and has a spe

ed of 32.2 m > s. The motorcycle has a speed of 14.8 m > s. What frequency does the motorcyclist hear?
Physics
1 answer:
Firdavs [7]3 years ago
8 0

To solve this problem it is necessary to apply the concepts related to Dopler's Law. Dopler describes the change in frequency of a wave in relation to that of an observer who is in motion relative to the Source of the Wave.

It can be described as

f = \frac{c\pm v_r}{c\pm v_s}f_0

c = Propagation speed of waves in the medium

v_r= Speed of the receiver relative to the medium

v_s= Speed of the source relative to the medium

f_0 =Frequency emited by the source

The sign depends on whether the receiver or the source approach or move away from each other.

Our values are given by,

v_s = 32.2m/s \rightarrow Velocity of car

v_r = 14.8 m/s \rightarrow velocity of motor

c = 343m/s \rightarrow Velocity of sound

f_0 = 523Hz \rightarrowFrequency emited by the source

Replacing we have that

f = \frac{c + v_r}{c - v_s}f_0

f = \frac{343 + 14.8}{343 - 32}(523)

f = 601.7Hz

Therefore the frequency that hear the motorcyclist is 601.7Hz

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Liono4ka [1.6K]

Answer:

10s

Explanation:

If it took Beatrice 25 seconds to complete the race

Distance = 100 meter

Beatrice speed = 100/25

                          = 4m/s

If Alice runs at a constant speed and crosses the finish line $5$ seconds, she must have completed the race in 20s (25 -5).

Her speed where constant

= 100/20

= 5 m/s

It would take Alice

= 50/5

= 10s

It would take Alice 10s to run $50$ meters.

5 0
3 years ago
A planet's temperature depends on its distance from the Sun as well as the strength of its greenhouse effect. Let's remove the e
pishuonlain [190]

Answer:

Smallest Effect

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5 0
3 years ago
The quadriceps muscles pull on the patella simultaneously. Below are the forces from each
Nostrana [21]

Based on the calculation of the resultant of vector forces:

  1. the resultant force due to the quadriceps is 1795 N
  2. the resultant force due to the quadriceps is 1975 N. Training and strengthening the vastus medialis results in a greater force of muscle contraction.

<h3>What is the resultant force due to the quadriceps?</h3>

The resultant of more than two vector forces is given by:

  • F = √Fₓ² + Fₙ²

where:

  • Fₓ is the sum of the horizontal components of the forces
  • Fₙ is the sum of the vertical components of the forces
  • Fx = F₁cosθ + F₂cosθ + F₃cosθ + F₄cosθ
  • Fₙ = F₁sinθ + F₂sinθ + F₃sinθ + F₄sinθ
  • F₁ = 680N, θ = 90 = 30 = 120°
  • F₂ = 220 N, θ = 90 + 16 = 106°
  • F₃ = 600 N, θ = 90 + 15 = 105°
  • F₄ = 480 N, θ = 90 - 35 = 55°

then:

Fx = 680 * cos 120 + 220 * cos 106 + 600 * cos 105 + 480 * cos 55

Fx = -280.6 N

Fₙ = 680 * sin 120 + 220 * sin 106 + 600 * sin 105 + 480 * sin 55

Fₙ = 1773.1 N

then:

F = √(-280.6)² + ( 1773.1)²

F = 1795.16 N

F ≈ 1795 N

Therefore, the resultant force due to the quadriceps is 1795 N

<h3>What would happen if the vastus medialis was trained and strengthened to contract with 720N of force?</h3>

From the new information provided:

  • F₁ = 680N, θ = 90 = 30 = 120°
  • F₂ = 220 N, θ = 90 + 16 = 106°
  • F₃ = 600 N, θ = 90 + 15 = 105°
  • F₄ = 720 N, θ = 90 - 35 = 55°

then:

Fx = 680 * cos 120 + 220 * cos 106 + 600 * cos 105 + 720 * cos 55

Fx = -142.95 N

Fₙ = 680 * sin 120 + 220 * sin 106 + 600 * sin 105 + 720 * sin 55

Fₙ = 1969.72 N

then:

F = √(-142.95)² + ( 1969.72)²

F = 1974.9 N

F ≈ 1975 N

Therefore, the resultant force due to the quadriceps is 1975 N.

Training and strengthening the vastus medialis results in a greater force of muscle contraction.

Learn more about resultant of forces at: brainly.com/question/25239010

3 0
2 years ago
A projectile is launched horizontally from a height of 8.0 m. The projectile travels 6.5 m before hitting the ground.
Effectus [21]
Time it takes the projectile to hit the ground after being thrown up:

√h/1/2a

√8/(.5)(9.81)

√8/4.905

√1.630988787

= 1.277101714

= 1. 28

hope this helps :)
7 0
3 years ago
A kid applies a force of 70 N to a ball over 1.1 meters. How much work did he do on the ball?
LekaFEV [45]

Answer:

77J

Explanation:

Not really an explanation to this, I just had this lesson last year and remembered it.

Hope I helped! ☺

8 0
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