A lever is placed on a fulcrum. A rock is placed on the left end of the lever and a downward (clockwise) force is applied to the right end of the lever. What measurements would be most effective to help you determine the angular momentum of the system?
a. the angular velocity and mass of the rock
b. the angular velocity and mass of the rock, and the radius of the lever
c. the velocity of the force, the radius of the lever, and the mass of the rock
d. the mass of the rock, the length of the lever on both sides of the fulcrum, and the force applied on the right side of the lever

b. the angular velocity and mass of the rock, and the radius of the lever

Explanation:

Angular momentum = angular velocity x moment of inertia of rock

moment of inertia of rock = mass of rock x (distance of rock from fulcrum)²

moment of inertia of rock = mass of rock x (radius of the lever )²

so measurement of moment of inertia  requires measurement of mass of rock and radius of lever.

Hence for measurement of angular momentum we require three physical quantities

1 ) angular velocity

2 ) mass of rock

3 ) radius of lever .

the electric field is a “force field” around a charged object that illustrates the direction the electric force would push an imaginary 

he made 11 calls in one day