07
7. The tension in the string AB is (pulley and string are massless)
(1) 15 N (2) 10 N
(3) 20 N (4) 30 N
From F.B.D of 1kg mass we get:-
T + ma = mg
=>T+ a = 10 (becuase m=1kg)
=>a=10 - T...eq;-(1)
From F.B.D of 3kg mass we get:-
T=Ma +Mg
a=(T-30)/3 (because m=3kg) ...eq(2)
from 1 and 2 we get:-
10-T = (T-30)/3
=>30-3T=T -30
=>4T=60
=>T = 15 N
So the correct option is (1)
not (4)
T + ma = mg
=>T+ a = 10 (becuase m=1kg)
=>a=10 - T...eq;-(1)
From F.B.D of 3kg mass we get:-
T=Ma +Mg
a=(T-30)/3 (because m=3kg) ...eq(2)
from 1 and 2 we get:-
10-T = (T-30)/3
=>30-3T=T -30
=>4T=60
=>T = 15 N
So the correct option is (1)
not (4)