Question

A former student of mechanics wishes to weigh himself but has access only to a scale a with capacity limited to 120 lbs and a small 20-lb spring dynamometer
b. with the rig shown he discovers that when he exerts a pull on the rope so that b registers 16 lb, the scale a reads 100 lb. what is his correct weight?

Answer 1

Answer:

The answer to the question is

The correct weight of the former student = 116 lbf

Explanation:

To solve the question, we list out the known variables as follows

Capacity of the scale = 120 lbs

Capacity of the spring dynamometer = 20 lbs

Reading on the scale = 100lb

Reading on the spring dynamometer= 16 lb

at equilibrium, sum of forces = 0

Therefore weight of former student = reaction forces of the scale + the reaction force of the spring dynamometer = 100lb + 16 lb = 116 lb

The correct weight = 116lb weight or 52.62 kg

Converting to weight which is a force = mass * acceleration = 52.62 kg * 9.81 m/s² =

516.2 N = 116 lbf