The simply supported beam is built up from three boards by nailing them together as shown. The wood has an allowable shear stress of Tanow = 1.S MPa, and an allowable bending stress of O'auow = 9 MPa The nails are spaced at s = 75 mm, and each has a shear strength of 1.5 kN. Determine the maximum allowable force P that can be applied to the beam.
PY 205 Week 3 Notes Chapter 4 and 5 Newton’s Laws 1. Velocities don’t change unless a net force acts upon it (qualitative) 2. The acceleration of a body is directly proportional to the net force acted on it (quantitative) a. Fnet = (mass)(acceleration) 3. Forces occur between two objects – if A exerts a force on B then B exerts a negative force on A. a. Fnet = Fxi +Fyj + Fzk b. The sum of all the forces on x = ma(x) c. The sum of all the force on y = ma(y) Applications of Newton’s laws - Kinetic motion - sliding friction - The force acts opposite to the direction of the object’s velocity - Normal force = shows that the friction force is approximately proportional to the normal force – the force that either object exerts on the other side and is perpendicular to their common surface contact o Force = Fnormal X the constant - Static friction – when a force parallel to the two surfaces can arise even when they are not sliding o Exceeding the maximum coefficient – where the constant is the coefficient of static friction