20241212

When using a wedge to lift or separate a heavy object, which of the following statements about the relationship between friction and the wedge is correct?

• Friction reduces the efficiency of the wedge because part of the applied force is used to overcome friction.

• As the coefficient of friction increases, the force required to move the wedge also increases, especially for wedges with larger angles.

• The effectiveness of a wedge is independent of friction and depends only on its geometry (e.g., the wedge angle).

• If the coefficient of friction is zero, the force required to move the wedge is minimized and depends only on the wedge's geometry.

Which of the following is incorrect about dry friction?

• Dry friction depends on the contact area between the surfaces.

• The coefficient of friction depends on the roughness and material of the surfaces in contact.

• The limiting static friction force is always greater than the kinetic friction force.

• Dry friction acts opposite to the direction of motion or intended motion.

According to the sign convention for internal forces in this class, which of the following is correct for shear force and bending moment?

• Shear force is positive when it causes clockwise rotation of the segment.

• Shear force is negative when it causes clockwise rotation of the segment.

• Bending moment is positive when it causes compression on the top fiber of the beam.

• Bending moment is positive when it causes tension on the top fiber of the beam.

At which point in a beam is the bending moment typically at its maximum value?

• Where the shear force is maximum

• Where the shear force is zero

• Where the load is concentrated

• At the supports

• The cable will not break and the truck will not slide if unsecured

• The cable will not break and the truck will slide if unsecured

• The cable will break and the truck will slide if unsecured

• The cable will break and the truck will not slide if unsecured