In the pulley-block system shown in figure, strings are light. Pulleys are massless and smooth. System is released from rest. In `0.3` seconds.
.
(a) work done on `2 kg` block by gravity is `6 J`
(b) work done one `2 kg` block by string is `-2 J`
( c) work done on `1 kg` block by gravity is `-1.5 J`
(d) work done on `1 kg` block string is `2 J`.

Options

A. only `a,d` are correct
B. only `b,d` are correct
C. only `a,b,c` are correct
D. All are correct

Answer

D

Explanation

`a = ((2m_(1)-m_(2)))/((2m_(1)+(m_(2))/(2)))g, T = ((3m_(1)m_(2))/(4m_(1)+m_(2)))g`
On `2 kg` block, `W_(1) = m_(1)gx = m_(1)g ((1)/(2) at^(2))` ,
`W_(T) = T xx x = T ((1)/(2) at^(2))`
On `1 kg` block, `W_(2) = m_(2) g "(x)/(2)`.