Question

Materials lectures:

1- A wire 0.00108 m in diameter and 1.5 m in length is used to support a load of 37 kg. The wire increases in length by 0.00088 m. To 3 significant figures, what is Young's Modulus of the wire in SI units of force per area? (answer: 6.75e11 N/m^2)

2- The atmospheric pressure above a fresh water lake is 101.2 kPa. What is the pressure in pascals at 12.1 m below the surface? (answer: 2.20e5 Pa)

3- Two students stand on two vertical pistons. The pistons are circular disks of equal mass. The pistons are connected by a volume completely filled with oil. (See figure below) The first student has a mass of 56 kg and the piston's working face, the one in contact with the fluid, has a radius of 0.16 m. The second student has a mass of 69 kg. The two pistons are in equilibrium with the students standing on the pistons. What is the radius in metres of the second piston's working face? (answer: 0.178 m)

Answer 1