Question

. A block of mass 5 kg is being raised vertically
upwards by the help of string attached to it. It
rises with an acce. of 2 m/s². The work done by
tension in the string if block rises by 2.5 m
(A) 125 J
(B) 147.5 J
(C) 193.4 J
(D) -87.5 J​

Answer 1

As mass 'm' is raised vertically

upward with acceleration 'a' then

tension in the string can be given

as

T - mg = ma

or, T = mg+ma

= m(a+g)

= 5(2+10)

= 5×12 = 60 N

Now, W = T × s

= 60×2.5

= 150 Joule.