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LuckyWell [14K]

3 years ago

14

A police car chases a speeder along a straight road towards a cliff both vehicles move at 160km/h the siren on the police car pr

oduces sound at a frequency of 100hz calculate Doppler shift in the frequency heard by the driver in a car behind the police at 120km/h moving towards the cliff and velocity if sound in air is 330m/s

1 answer:

natta225 [31]3 years ago

4 0

Answer:

f ’= 97.0 Hz

Explanation:

This is an exercise of the doppler effect use the frequency change due to the relative movement of the fort and the observer

in this case the source is the police cases that go to vs = 160 km / h

and the observer is vo = 120 km / h

the relationship of the doppler effect is

f ’= f₀ (v + v₀ / v- $v_{s}$ )

let's reduce the magnitude to the SI system

v_{s} = 160 km / h (1000 m / 1km) (1h / 3600s) = 44.44 m / s

v₀ = 120 km / h (1000m / 1km) (1h / 3600s) = 33.33 m / s

we substitute in the equation of the Doppler effect

f ‘= 100 (330+ 33.33 / 330-44.44)

f ’= 97.0 Hz

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3 years ago

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Consider an eraser, weighing 20g, sitting 5cm from the center of a turntable (flat disk attached to a motor which can spin the d

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B. Centripetal Force

Explanation:

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Let g = 9.8 m/s2

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$F_f = N\mu = mg\mu = 0.02*9.8*0.1 = 0.0196 N$

For the eraser to begin slipping, its centripetal acceleration must win over the acceleration created by friction force, which is

$a_f = F_f / m = 0.0196 / 0.02 = 0.98 m/s^2 = a_c$

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where r = 0.05 is the radius of rotation, which is distance from the center to the eraser

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If it spins and angle of 4.43 rad per second then for every minute (60 seconds) it would spin an angle of 4.43 * 60 = 265.6 rad/min

Since 1 revolution is 2π rad, then in a minute it would spin 265.6 / 2π = 42.3 revolution/minute

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3 years ago

A duck has a mass of 2.40 kg. As the duck paddles, a force of 0.150 N acts on it in a direction due east. In addition, the curre

Akimi4 [234]

Answer:

Explanation:

Given

mass of duck=2.40 kg

$F_1$ =0.150 N

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$a_x=\frac{0.263}{2.4}=0.109 N$

net force in Y direction

$F_y=0.160\times \sin 45=0.113 N$

$a_y=\frac{0.113}{2.4}=0.047 m/s^2$

Thus displacement in x direction

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$x=0.15\times 2.8+\frac{0.109\times 2.8^2}{2}=0.847 m$

Displacement in Y direction

$Y=ut+\frac{at^2}{2}$

here u=0

$Y=0+\frac{0.047\times 2.8^2}{2}=0.184 m$

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Answer:

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The kinetic energy of the block is given by:

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3 years ago