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|dw:1344703864992:dw|the back tire pushes trying to move clockwise, and static friction's reactive force pushes to the right the wheel in the from is being pushed by a force of friction to the left (due to the relative motion of the ground, as you said) which also causes the tire to move clockwise I misspoke to say that static the friction has no direction in this case, that's why I needed to draw it
wheel in the front*
so will the back tire continue to rotate clockwise even when friction pushes it to the right/forward??
we force the tire to move clockwise by turning the pedals. the force acting to the left is the reactive force of friction of the ground on the tire hence the friction on the back tire is a result of us *forcing* the tire to move clockwise, so yes the wheel will move that way
at the bottom of the tire we have a balance of forces|dw:1344704471674:dw|this is the force that the tire exerts on the ground due to our pedaling (human power) since there is not slippage of the back wheel this force must be balanced by friction\[\vec F=-\vec f\]hence friction points forward, which causes the bike to move forward
ok thanks can u explain the friction and motion of a car also plz
it is identical, but with double tires and a motor instead of a human to power it
forward force on backward tires and vice versa??
in terms of friction yes unless it is four-wheel drive, then the force of friction acts forwards for all tires
...because there is a motor pushing the front tires as well in 4-wheel drive make sense?
yeah i think so.... so all tires are pushed forward. what happens while braking??
the car slows down so what direction must friction be acting?
careful in your wording of the situation btw in a 4-wheel drive the four tires are pushing against the ground *opposite* the direction of the car's motion (backwards) however friction pushes opposite that, hence the car moves forward
...force of motor against the ground I mean
do all tires experience backward frictional force while braking? and while moving and breaking is the friction static or kinetic?
I already explained that while moving the friction is static (that is why the forces sum to zero and friction acts forward) while breaking the car is skidding (slipping) and slowing down. any wheels that lock due to the breaks will be skidding against the ground is that static or kinetic? is it into or opposite the direction of motion?
ok so its kinetic while braking and opp to motion right?
thanks a lot :)