This type of listening response is called back-channel signal. This allows the speaker to know that the listener is attentive or willing to engage a conversation between them. It is shown through short utterances, facial expressions, head nods and others.
The force on the ship is more than a car
It is defined by their wavelength. Different colors have different wavelengths. For example, radio waves have a really long wavelength, whereas gamma-rays have a very short wavelength.
