Here are a few questions on the friction -

Que 1 : You are standing with your bag in your hands on the ice in the middle of a pond . The ice is so slippery that it can offer no friction . How can u come out of it ?????

 

Que 2 : While walking on ice , one should take small steps to avoid slipping . This is bcoz smaller steps ensure -

(a) larger friction

(b) smaller friction 

 

Pls post solutions with explanation !!!!!!

ans:1 in that the direction opp. in which u want to go

 coz when u throw a bag then a backward reaction force apply on yr body.

 

ans:2 when we walk then we press the surface backwards & same amount of friction force is applied in forward direction.so when we walk on the ice we take small steps to ensure smaller friction.

I agree with ans 1 , but I am not able to understand ans 2 . If friction would be large , then it would be easier to walk on ice !

Pls explain !!!!!

In case 2 when u take smaller steps, it is actually an advantage to you bcos:

Say u have 10m of ice.We know that both smaller and larger steps give u same friction. But, in a larger step,say of 5m, u will cross the pond in two steps and it means u get friction twice. In a smaller step, say 2m, u get friction 5 times which is of greater advantage. Hence, smaller steps are preferred.

one more way to come out of the ice is to breathe in nicely and blow it out in the direction opposite to the motion. this will mke u move in the direction u want.

 

normal reaction is the force xerted by the molecules of the surface in the direction opposite to the force applied. while takin big steps the force applied to deform the surface is acting at an angle and is equal to mgcos. and here normal reaction is equal to mgcos.as _{[ ][0 ]} mgcos  ( the person is takin small steps, hence  decreases),mgcos becomes equal to mg and hence normal reaction also increases as compared while takin big steps. therefore the friction provided also increases in case of small steps. and above that the surface area is less in ase of big steps since there is less probability that the whole feet will land 2gether on the ground. as in teh case of small steps the probability is more and hence interlocking of the irregularities is more which results in more friction.

 

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