Answer:
12.3 m/s
Explanation:
The Doppler equation describes how sound frequency depends on relative velocities:
fr = fs (c + vr)/(c + vs),
where fr is the frequency heard by the receiver,
fs is the frequency emitted at the source,
c is the speed of sound,
vr is the velocity of the receiver,
and vs is the velocity of the source.
Note: vr is positive if the receiver is moving towards the source, negative if away.
Conversely, vs is positive if the receiver is moving away from the source, and negative if towards.
Given:
fs = 894 Hz
fr = 926 Hz
c = 343 m/s
vs = 0 m/s
Find: vr
926 = 894 (343 + vr) / (343 + 0)
vr = 12.3
The speed of the car is 12.3 m/s.
Answer:
6.49707626552 m/s
4.45147808359 m
1.46212197842 s
Explanation:
t = Time taken
u = Initial velocity
v = Final velocity
s = Displacement
a = Acceleration
g = Acceleration due to gravity = 9.81 m/s²
![v^2-u^2=2as\\\Rightarrow v=\sqrt{2as+u^2}\\\Rightarrow v=\sqrt{2\times 34.6\times 0.61+0^2}\\\Rightarrow v=6.49707626552\ m/s](https://tex.z-dn.net/?f=v%5E2-u%5E2%3D2as%5C%5C%5CRightarrow%20v%3D%5Csqrt%7B2as%2Bu%5E2%7D%5C%5C%5CRightarrow%20v%3D%5Csqrt%7B2%5Ctimes%2034.6%5Ctimes%200.61%2B0%5E2%7D%5C%5C%5CRightarrow%20v%3D6.49707626552%5C%20m%2Fs)
The speed with which Sam releases the ball is 6.49707626552 m/s
![v^2-u^2=2as\\\Rightarrow s=\dfrac{v^2-u^2}{2g}\\\Rightarrow s=\dfrac{0^2-6.49707626552^2}{2\times -9.81}\\\Rightarrow s=2.15147808359\ m](https://tex.z-dn.net/?f=v%5E2-u%5E2%3D2as%5C%5C%5CRightarrow%20s%3D%5Cdfrac%7Bv%5E2-u%5E2%7D%7B2g%7D%5C%5C%5CRightarrow%20s%3D%5Cdfrac%7B0%5E2-6.49707626552%5E2%7D%7B2%5Ctimes%20-9.81%7D%5C%5C%5CRightarrow%20s%3D2.15147808359%5C%20m)
The ball reaches a height of 2.3+2.15147808359 = 4.45147808359 m
Distance to his head from the maximum height is 4.45147808359-1.83 = 2.62147808359 m
![s=ut+\frac{1}{2}gt^2\\\Rightarrow 2.62147808359=0t+\frac{1}{2}\times 9.81\times t^2\\\Rightarrow t=\sqrt{\frac{2.62147808359\times 2}{9.81}}\\\Rightarrow t=0.731060989212\ s](https://tex.z-dn.net/?f=s%3Dut%2B%5Cfrac%7B1%7D%7B2%7Dgt%5E2%5C%5C%5CRightarrow%202.62147808359%3D0t%2B%5Cfrac%7B1%7D%7B2%7D%5Ctimes%209.81%5Ctimes%20t%5E2%5C%5C%5CRightarrow%20t%3D%5Csqrt%7B%5Cfrac%7B2.62147808359%5Ctimes%202%7D%7B9.81%7D%7D%5C%5C%5CRightarrow%20t%3D0.731060989212%5C%20s)
Time taken to go down to his head is 0.731060989212 seconds from the maximum height
Time taken from the moment the ball left his head height = 0.731060989212+0.731060989212 = 1.46212197842 s
A magnetic field is a force field, invisibly pushing electrically charged objects just as a gravitational field pulls objects with mass. Whereas all objects with mass exert a gravitational field, however, not all objects have a magnetic field. Magnetic fields are created by electrical charges. Thanks to their structure at the atomic level, some substances -- like the iron in magnets -- have a permanent magnetic field.