Question

Two blocks of masses $7kgand5kg$ respectively are connected by a heavy rope of mass $4kg$. An upward force of $200N$ is applied as shown in the diagram. The tension at the top of heavy rope at point P is: $(g=10m/s^2)$

• A. $2.27N$
• B. $112.5N$
• C. $87.5N$
• D. $360N$

Answer 1

The correct option is B $112.5N$

first we have to calculate resultant force to calculate acceleration of the system

$F-mg=ma$

where m is the mass of whole system

$200-16\times g=16a$

$a=2.5m/s^2$

now tension at point P is

$T-mg=ma$

here $m$ is the mass of the string and lower block

$T=9\times g+9\times 2.5=112.5N$