basics on mechanics

5 Answers

1
venkateshan ·

2nd question is dat.... suppose in the question to find the acceleration of the block and and force of friction, if both the coefficient of static ass well as kinetic frriction is given then which one to use to get proper solution......

49
Subhomoy Bakshi ·

well...

look...

if the 15kg block moves a distance x, in order to keep the 2 strings taut and also to ensure they dont snap, the other 2 masses must move a distance x...

by similar logic, all the 3 blocks must have same acceleratio through out their journey and same velocity also (provided the strings were taut from the beginning)...

thus the accn is a

now drawing FBD of each block separately and writing eqns,,,

15g-T=15a

T-T'-f=5a
f≤μN
N=5g

T'-5g=5a!

here take limiting case...i.e. f=μN...if accn is +ve then they move else they do not...(why?)

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1
venkateshan ·

hey subho... can u plz tell me in diff concept why the accl. will be same.....

106
Asish Mahapatra ·

@venkateshan : look the string remains strectched tight doesnt it ? it nvr becomes loose .. (just using terms in loose real world sense ) ..

Consider two bodies attached to one another with a string and ur pulling one of d bodies..

What will u see ? will one object move faster than the other OR will the relative distance between them remain the same ???

1
venkateshan ·

ya...it 'll remain da same....

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