Exam 14: Statics and Elasticity

An I-beam having a mass of 810 kg and length of 5.1 m has one end attached to a vertical wall.The I-beam is allowed to pivot up and down about the attachment location. A cable is then attached from the vertical wall to the other end of the I-beam. The cable makes an angle of 31º with the I-beam, and the I-beam is horizontal (parallel with the ground). The tension in the cable is

Five cubes (each edge of a cube is 5 cm) are each laid on the top of a table (cubes are not stacked). If each cube weighs 5 N, the pressure exerted on the table is

A 4-m-long ladder (mass = 56 kg) leans against a frictionless wall. The base of the ladder makes an angle of 55(which is not the maximum frictional force) with the rough floor, having $\mu _ { s } = 0.5$ . The horizontal force exerted by the frictionless wall that acts on the ladder is

A 4-m-long I-beam (of uniform shape) having a mass of 48 kg is held at a 35º angle above the floor by a bracket attached to its end. The bracket is securely bolted to the floor. The torque that the bracket must provide to hold the I-beam in place is

A 10-meter-long steel rod (Young's modulus of $2 \times 10 ^ { 11 }$ Pa) having a 0.8-cm radius is supporting a 500-kg mass. The change in the length of the rod is

A metal sphere (bulk modulus of $1 \times 10 ^ { 11 }$ Pa) is put under a hydraulic pressure of $10 ^ { 10 }$ Pa. If the original volume of the sphere was 1 cm $3$ , the new volume of the sphere is

If a rigid body is in rotational equilibrium, all of the following statements are valid except

Consider a truss designed to support some maximum weight W on a frictionless, horizontal surface. The truss has three straight members joined as in the letter "A," and all members of the truss are weightless. W is placed at the apex of the truss. A single modification that would permit stable support of a weight heavier than W would include any of the following except

Five cubes (each edge of a cube is 5 cm) are each laid on the top of a table (the cubes are not stacked). If each cube weighs 5 N, the net force exerted on the table is

A 4-m-long ladder (mass $= 56 \mathrm {~kg}$ ) leans against a frictionless wall. The base of the ladder makes an angle $\theta$ with the rough floor $\left( \mu _ { s } \right)$ . If $\mu _ { s } = 0.5$ , the minimum value of $\theta$ , such that the ladder will not slip, is