Friction force is when you rub 2 things together and they get warm. Motion, on the other hand, is if your walking along the sidewalk - you hardly get warmer -------
Unless it's a colder day outside and you're walking SO you decide to rub your hands together to get warm, but if you were just walking , its motion and only motion - no friction :):)
A. Internal. Most cars use that type of set up because it's more efficient, you can find more about it on this website, https://auto.howstuffworks.com/did-cars-ever-have-external-combustion-engines.htm
:)
~ Ria
A 300-kg bear grasping a vertical tree slides down at constant velocity. The friction force between the
tree and the bear is
Frequency = (speed) / (wavelength)
Speed = 3 x 10⁸ m/s
Wavelength = 3 cm = 0.03 m
Frequency = (3 x 10⁸ m/s) / (0.03 m)
Frequency = (3 x 10⁸ / 0.03) (m / m-s)
Frequency = 1 x 10¹⁰ Hz (10 Gigahertz)
