Answer:
f = 0.75 Hz
Explanation:
It is given that, a person is kicking there legs three times every four seconds. We need to find his frequency. The number of times an event is occurring is called frequency of an object. The frequency of a person is given by :

So, the frequency of the person is 0.75 Hz.
The car is moving with velocity 1m/s
This is because of conservation of linear momentum.
Answer:
A signal is produced.
Radio waves are modulated and amplified.
Radio waves are amplified and demodulated.
A signal is seen, heard, or used.
Explanation:
Communication is the method of transmitting information between two or more participants. A radio communication network is a set of static and wireless radio equipment developed to facilitate an entity by enabling particular modes of communication such as one-to-many and one-to-one communication. Radio waves are being used to transmit information spatially from the sender to receiver, by modulating the radio signal in the transmitter. The above steps explains the loop of the radio communication system.
Distance between the centers of the two objects are the second object
Answer: You use it to cook food so you can eat. put whatever kind of food you like in there and heat it up for how long you want and then it will beep when done. then you can eat!