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Travka [436]
3 years ago
12

A person watches an ambulance drive by them while emitting a steady sound from its siren. When the ambulance passes the person (

switching from moving towards him to moving away from him), the perceived frequency of the sound he receives decreases by 11.2 percent. How fast is the ambulance driving
Physics
1 answer:
Dmitrij [34]3 years ago
6 0

Answer:

21.7 m/s

Explanation:

Let the velocity of ambulance is v and f is the real frequency of siren of ambulance.

the velocity of sound is 343 m/s

use the formula of Doppler's effect

f' = \frac{343}{343-v}f    .... (1)

where, f' is the frequency of at the first time.

Now the source is moving away from the person, the frequency is given by

f'' = \frac{343}{343+v}f    .... (2)

According to the question,

f'' = f' - 11.0 % of f'

f'' = 0.881 f'

By equation (1) and (2)

\frac{343}{343+v}f= \frac{343}{343-v}\times 0.881f

40.817 = 1.881 v

v = 21.7 m/s

Thus, the speed of ambulance is 21.7 m/s.

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Using the strap at an angle of 31.0° above the horizontal, a Grade 12 Physics student, tired from studying, is dragging his 15.0
lora16 [44]

Answer:

<h2>154.73N</h2>

Explanation:

The question is incomplete. Here is the complete question.

Using the strap at an angle of 31° above the horizontal, a Grade 12 Physics student, tired from studying, is dragging his 15 kg school bag across the floor at a constant velocity. (a) If the force of tension in the strap is 51 N, what is the normal force.

Check the diagram related to the question in the attachment below for better understanding.

The normal force is the reaction acting perpendicular to the force of tension in the strap and opposite the weight of the bag. They are the forces acting along the vertical.

The normal force N will be the sum of the force of tension acting along the vertical (Ty) and the weight of the bag (W).

Ty = 15sin31°

Ty = 7.73N

W = mass * acceleration due to gravity

W = 15.0*9.8

W = 147N

The normal force is therefore expressed as;

N = Ty + W

N = 7.73 + 147

N = 154.73N

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3 years ago
Differentiate between s-block and p-block​
alexandr402 [8]

Explanation:

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You push against a steamer trunk with a force of 800 n at an angle alpha with the horizontal . the trunk is on a flat floor and
galina1969 [7]
The formula for this problem that we will be using is:
F * cos α = m * g * μs where:F = 800m = 87g = 9.8
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α = arccos 0.59 = 54 ° is the largest value of alpha
6 0
3 years ago
A manometer is used to measure the air pressure in a tank. the fluid used has a specific gravity of 1.25, and the differential h
BartSMP [9]
Specific Gravity of the fluid = 1.25 
Height h = 28 in
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 Density of water = 62.4 lbm/ft^3 at 32F
 Density of the Fluid = Specific Gravity of the fluid x Density of water = 1.25 x 62.4
 Density of the Fluid p = 78 lbm/ft^3
 Difference in pressure as we got the differential height, dP = p x g x h  dP = (78 lbm/ft^3) x (32.174 ft/s^2) x (28/12 ft) [ 1 lbf / 32.174 ft/s^2] [1 ft^2 /
144in^2]
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 (b) Pressure in the tank that is at Lower
 P = Atmospheric Pressure + Pressure difference = 12.7 + 1.26 = 13.96psia
4 0
3 years ago
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