Answer:
The external force leads to an increase on gravitational and spring potential energies.
Explanation:
The system consists of a mass, resort and Earth. According to the Principle of Energy Conservation there is a potential energy as a consequence of the interaction between Earth and the mass and spring potential energy because of the spring deformation and, besides, the existence of work due to an external force:



![F\cdot \Delta r = G\cdot m \cdot M \cdot \left(\frac{1}{r_{o}-\Delta r}-\frac{1}{r_{o}} \right)+\frac{1}{2}\cdot k \cdot [(x_{o}+\Delta r)^{2} -x_{o}^{2}]](https://tex.z-dn.net/?f=F%5Ccdot%20%5CDelta%20r%20%3D%20G%5Ccdot%20m%20%5Ccdot%20M%20%5Ccdot%20%5Cleft%28%5Cfrac%7B1%7D%7Br_%7Bo%7D-%5CDelta%20r%7D-%5Cfrac%7B1%7D%7Br_%7Bo%7D%7D%20%20%20%5Cright%29%2B%5Cfrac%7B1%7D%7B2%7D%5Ccdot%20k%20%5Ccdot%20%5B%28x_%7Bo%7D%2B%5CDelta%20r%29%5E%7B2%7D%20-x_%7Bo%7D%5E%7B2%7D%5D)
The external force leads to an increase on gravitational and spring potential energies.
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Answer: Doppler effect
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Explanation:
A radar gun (also known as a Doppler radar) uses the Doppler effect when measuring "return echoes" after having sent a microwave signal (a type of electromagnetic radiation).
In this context the Doppler effect consists of the change in a wave perceived frequency when the emitter of the waves, and the observer move relative to each other.
In the case of radars, a microwave signal is sent to a target (the tennis or baseball in this case) and then is reflected after "hitting" the target, so that the radar system measures this difference between the sent signal and the reflected signal.
Answer:
True
Explanation:
Magnetic field lines outside of a permanent magnet always run from the north magnetic pole to the south magnetic pole. Therefore, the magnetic field lines of the earth run from the southern geographic hemisphere towards the northern geographic hemisphere.
Speed= freq x wavelength
if freq is doubled the wavelength will halve for constant speed