Question

A dynamometer D (Fig.) is connected to two masses M and m. Forces of F and f are applied to the masses. The values of M and m are 10 kg and 10 g respectively and of F and f are 2 and 1 kg-wt respectively. What will happen to the masses and what will be the reading on the dynamometer if: 

(a) the force F is applied to the larger mass and the force f to the smaller one; 

(b) the force F is applied to the smaller mass and the force f to the larger one. What will be the reading on the dynamometer if M and m are both equal to 5 kg?

Answer 1

Answer: The dynamometer reading will be 

Explanation:

In all three cases, the system will move with some acceleration a in the direction of the larger force, and the dynamometer will indicate the coupling force f_n acting between the 

masses. To find the magnitude of f_n, it is necessary to write the the equation for Newton's second law for each mass separately. For the first case (Fig.)

the conditions expressing the ratios of the masses, we may solve the remaining cases.