dynamics problem

[grumpy]

1.is frictional force a reaction force.?

e.g when we walk there is force of friction that allow us to walk.if there isnt any friction we cant walk.
my question is that if there is no friction there will be reaction from the ground when someone will walk,why doesnt he walk then.
if friction is a reaction force then why it is less than the driving force very often.


2.how frictional force provides a centripetal force when turning a car.


please answer these two questions and please be quick

 

[beacon_of_light]

It's the direction. If there is no friction, reaction force from ground is perpendicular to surface. On a flat surface, that's straight up. Useful for not falling towards the center of the planet, not so much when you try to move. If you ever lost footing on ice, you should have some idea of what it's like. Except, on ice you can get a grip if you are careful, because there is still some friction.

As far as friction itself, which one you call action and which you call reaction is matter of preference, really. But yes, the ground always pushes on you as much as you push on it. That's true for vertical and horizontal components. No getting around that.


When you make a turn, the car would "like to" continue traveling in the straight line, but that would require tires to slip relative to ground. The force preventing the slipping is the static friction force. Since the wheel rolls along direction of motion, there is no static friction in that direction. You get a force that's perpendicular to direction of travel and points into the turn. That's your centripetal force which keeps the car following the curve.
Hope you get that

 

[grumpy]

ok igot the second one perfectly.
but has enqueries about first one
what "it" is direction ?
secondly reaction force that you mentioned is for weight .i am not talking about weight i am talking about pushing forward force.