ENGR 107 – Introduction to Engineering Forces, Moments and Static Equilibrium (Lecture #7)

ENGR 107 - Introduction to Engineering Force ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Force A force may be thought of as any influence which tends to change the motion, i.e. the velocity and/or direction, of an object. ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Force A force has both a magnitude and a direction. Thus, it is a vector quantity. ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Force BX B BY R AY R = A + B A AX RX = AX + BX RY = AY + BY ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Moment ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Moment (Torque) The tendency of a force, F, to cause a rotation about an axis or point is called the moment, M, of the force with respect to that axis or point. ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Moment (Torque) ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Moment (Torque) d1 d2 P MP = F x d ENGR 107 - Introduction to Engineering

Moment (Torque) Example: Consider different forces acting on a body, at different distances from a point of rotation on the body. How does the force and distance effect the moment? ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Static Equilibrium ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Static Equilibrium A body is in static equilibrium if the sum of all of the forces and moments acting on the body is zero. ENGR 107 - Introduction to Engineering

Mathematically, this implies: S FX = 0 S FY = 0 S MP = 0 Static Equilibrium Mathematically, this implies: S FX = 0 S FY = 0 S MP = 0 ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Static Equilibrium Example: ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Static Equilibrium Example: ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Static Equilibrium Example: ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Static Equilibrium Example: ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Static Equilibrium Example: ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Static Equilibrium Example: ENGR 107 - Introduction to Engineering

ENGR 107 - Introduction to Engineering Static Equilibrium Example: ENGR 107 - Introduction to Engineering