Hey Guys, This is my first time posting ... sooo here it goes! I have spent the past hour trying to figure out how we walk (in a physics sense) - I can't seem to find anything good on google that really answers my question. I have a general idea that when i put my foot down, I push backwards against the floor and that causes the floor to push me forward. This is a very generic description though and I am trying to decompose the matter into FBD's. So this is my understanding thus far. When I wish to walk forward I plant my foot on the floor. Then I use my muscles to apply a force to my foot backwards. If there was no on the surface, the force applied to my foot would cause it to accelerate in a backwards direction and thus cause me to slip. Because there is friction, the force of static friction acts on my foot in the forward direction, balancing the force I applied. This causes my foot to be stationary. So here's my point of confusion...where does the force from the ground pushing back on me come from? All I can see here are two forces acting on my foot: 1.) my leg pushing my foot backwards 2.) static friction pushing my foot forwards, resulting in a 0 net force on the foot. If someone out there is listening, can you please explain how we are able to walk in terms of individual forces, so I can understand the picture completely? Also, I have one more question and that relates to turning a car. I was looking at an example in my physics book and it was describing a car going around a turn (uniform circular motion) on a road with certain friction coefficient. In the FBD, they only drew 3 forces: gravity, normal, and static friction force pointing into the turn (this was the centripetal force). I was confused as to how static friction came into play at all in this. Also, I don't understand how static friction acts alone in the horizontal direction. My understanding of static friction was that, when you apply a force to an object, static friction force appears and resists motion, upto the slip limit. For example, if a block is sitting on the floor, there is no static friction force. If I apply a force to the box, then there is a force of static friction to oppose my push. However, in this FBD in my book, there was just one horizontal force and that was the static friction force. I don't see how it would arise unless I was pushing the car laterally. Can someone please help me understand how the car is able to turn with a physically rigorous description (including forces exerted by the tire, etc.) because I am having the woorrst time trying to understand it! Thanks a lot for your help guys... really appreciate it!