A dynamometer D, which is a device used to measure force, is attached to two blocks of masses 6 kg and 4 kg. Forces of 20 N and 10 N are applied on the blocks as shown in the figure. The reading of the dynamometer is

Options

A. 10 N
B. 20 N
C. 6 N
D. 14N

Answer

D

Explanation

If a is the acceleration of the system , then
`a= ( " net force ")/(" total mass")= ( 20 -10)/(6+4)= 1ms^(-2)`
It is along the direction of ` vecF `
if R is the reading of the dynamometer then
`R +Ma =F or R = F - Ma = 20 - 6 xx 1 = 14 N`