The mass of a typical froghopper is 12.3 mg . how many newtons does it weigh

We are task to calculate for the weigh of a froghopper given only its mass of about 12.3 mg. To solve for this, we are going to use Newton's Second Law of Motion which in mathematical expression would be
F=ma
where F is the force acting on the object, m is the mass of an object and a is the acceleration acted on it.

Since the object is stationary, we assume the acceleration acted on it is in the vertical which is the acceleration due to gravity. Acceleration due to gravity is computed to be 9.81 m/.

The unit of force is in Newton which equivalent to kg m/.

We must convert mg to kg. We know that 1g=1000mg and 1kg=1000g.
For 12.3 mg=12.3mg x1g/1000mg x1kg/1000g =0.0000123 kg

To solve for the weigh,

F=0.0000123 kg x 9.81 m/.
F=0.000121 N

Therefore, the weight of a froghopper in Newton is 0.000121N.