This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
The forces acting on the block are  the weight (due to gravitation) and the tension force in the string pulling it upwards.
  Since the block is stationary and in equilibrium,  the two forces are equal and opposite.  Hence, the tension force exerted by the string on the block = weight = 15 N.

 The forces on the string at the lower end are :  tension in the string and the weight of the block.  Thus the force exerted by the block on the string is equal to the weight of the block = 15 N.

1 5 1