FORCE THAT ACTS DOWNWARD. IT IS BALANCED BY THE NORMAL FORCE EXERTED ON THE OBJECT HELD BY THE STRUCTURE. THE NORMAL FORCE IS A FORCE THAT ACTS UPWARD. AS LONG THE WEIGHT (DOWNWARD FORCE) IS BALANCED BY THE NORMAL FORCE (UPWARD FORCE), THE NET FORCE ACTING ON THE OBJECT IS ZERO AND THE OBJECT IS IN EQUILIBRIUM. WHEN AN OBJECT IS IN EQUILIBRIUM, THERE IS NO CHANGE IN MOTION, SO IT IS AT REST (AS IN THIS CASE) OR MOVES AT CONSTANT VELOCITY.

ACCORDING TO NEWTON'S THIRD LAW, THE NORMAL FORCE EXERTED BY THE STRUCTURE ON THE OBJECT IS EQUAL IN MAGNITUDE, BUT OPPOSITE IN DIRECTION TO THE WEIGHT OF THE OBJECT. IN OTHER WORDS, THE NORMAL FORCE THAT THE STRUCTURE EXERTS ON THE OBJECT IS EQUAL TO THE WEIGHT OF THE OBJECT UNTIL THE STRUCTURE FAILS.

ACCORDING TO NEWTON'S SECOND LAW, A NET FORCE CAUSES AN OBJECT TO ACCELERATE. IN THIS CASE, THE SUM OF THE NORMAL FORCE AND THE WEIGHT IS ZERO, REPRESENTS THE NET FORCE ACTING ON THE OBJECT. THERE IS NO ACCELERATION AND THE OBJECT REMAINS IN EQUILIBRIUM.

WHEN THE OBJECT FALLS, BREAKING THE STRUCTURE, THE NORMAL FORCE EXERTED BY THE STRUCTURE WAS INSUFFICIENT TO OFFSET THE WEIGHT OF THE OBJECT. THE NET FORCE IS NO LONGER ZERO. THE WEIGHT OF THE OBJECT IS GREATER THAN THE NORMAL FORCE. NOW, THE OBJECT ACCELERATES DOWNWARD UNTIL IT STRIKES A SURFACE WHOSE NORMAL FORCE WILL BALANCE THE OBJECT'S WEIGHT.

PREREQUISITES

STUDENTS MUST BE FAMILIAR WITH TERMS SUCH AS FORCE, NORMAL FORCE, AND WEIGHT. STUDENTS MUST BE FAMILIAR WITH NEWTON'S THREE LAWS OF MOTION.

SCHEDULE OF ACTIVITIES