What is an essential characteristic of an object in equilibrium?
a. zero velocity
b. zero acceleration
c. zero momentum
d. zero energy

Zero acceleration is an essential characteristic of an object in equilibrium

Explanation:

Equilibrium is a condition or state of a system where the internal energy or motion of the object doesn't change with time. Also the force acting on the object will be zero. According to “Newton's second law of motion”, the acceleration of the object in equilibrium will be zero. There are two types of equilibrium namely static equilibrium and dynamic equilibrium. Static equilibrium is a state where the net force acting on object will be zero and the object will not be moving. In Dynamic Equilibrium, the force on the object will be zero and the object will be moving with an non zero constant velocity.

answer:

d. because dr. laguardia selected a widely used measure, his study generalizes to has strong external validity. external validity has limited external validity. other applications of this measure.

the widely used measure that he applied to his experiment was the benton facial recognition test. it employed on to football players and as result, only players who suffered brain concussions did not pas this test. and although it has an external validity, it is limited because it isn't general to apply to other population.

"harry t. moore (1905-1951) – civil rights activist, leader, and the first martyr of the civil rights movement. fannie lou hamer (1917–1977) – leader in the american civil rights movement; co-founder of the national women's political caucus and freedom democratic party. james farmer (1920–1999) – congress of racial equality."