IIT JEE , AIEEE Forum - Physics , Mechanics

sathya_crazyteen

a man pushes s 35 kg crate on a floor with a force 110 N

and us= .37

does the crate move?

if another worker wants to help himm out and pulls the crate vertically ,what is the force has he to apply to get the crate moving

if the worker pulls horizontally whats the additinal force to b applied to move the crate?

chinmay_saxena01

no crate does not move....coz
f=usmg=129.126.8N>110N,,,,,so crate does not move,,,,,and to move the crate one have to overcome this force,,,,so required additional force 16.8N......AM I RIGHT?
IF YES THEN RATE ME PLZ.....

karthik2007

I am taking k as the coefficient of friction:

in the first case, find out kmg, as N = mg here.

If it is greater than 110N, the block wont move.

2nd part is a good question:

As the second worker pulls the block up, he is reducing the normal reaction, ie, let him apply a force of F upwards

N+F = mg

Hence N = mg-F

Also, for him to just push the block, 110 = k(mg-F)

everything but F is known, hence solve for F

for the 3rd part, its really simple:

Let the horizontal force be P:

P+110 = kN

Hence solve for P.

chinmay_saxena01

sorry i didn't read the question carefully

chinmay_saxena01

as worker pulls block upwards...so
f+R=mg
so R=mg-f (R=REACTION)
as one is pushing block so 110=usR
110=.37(35*10-f)
so f = 32.2 approx.

chinmay_saxena01

sorry mistake in my solution,,,,it was 53,,,,

varun.tinkle

IN THE FIRST CASE THE BLOCK CANNOT MOVE
LET HT EMAN PULL IN THE UPWARD DIRECTION WITH A FORCE F
N+F=MG
N=MG-F
FRICTION=UN
=0.37(350-F)
120=0.37(350-F)
110=129.5-0.37F
19.5=0.37F
F=52 N
PLS RATE ME IF U FIND ME USEFUL
!!!!!!!!!!!CHEERS!!!!!!!!!!!

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