With what acceleration ‘a’ shown the elevator descends so that the block of mass M exerts a force of on the weighing machine? [g = acceleration due to gravity]

To find the acceleration 'a' with which the elevator descends, we can use Newton's second law of motion.

Step 1: Identify the forces acting on the block of mass M. In this case, we have the force of gravity acting downwards (mg) and the normal force exerted by the weighing machine acting upwards (N).

Step 2: Since the block is exerting a force on the weighing machine, we can equate the force exerted by the block (mg) to the normal force (N). Therefore, we have mg = N.

Step 3: The normal force (N) can also be expressed as the product of the mass (M) and the acceleration (a). So, N = Ma.

Step 4: Substituting the value of N from step 2 into the equation from step 3, we have mg = Ma.

Step 5: Rearranging the equation, we get a = g.

Therefore, the acceleration 'a' with which the elevator descends so that the block of mass M exerts a force on the weighing machine is equal to the acceleration due to gravity (g).