A light particle of mass m is connected to another very heavy particle by means of a light inextensible string that passes over a smooth pulley. The reading of the spring balance is approxinately

Options

A. `4 mg`
B. `gt gt mg`
C. zero
D. `2 mg`

Answer

A

Explanation

`T = (2m_(1)m_(2)g)/(m_(1) + m_(2))`
`m_(1) = m`
`m_(2) =` very heavy mass (M)
`T = (2mg)/((m+ M)/(M))`
`T = (2mg)/(1 + (m)/(M))`
`T ~~ 2mg" " m lt lt M`
spring balance will measure
`2T = 2 xx 2mg = 4 mg`