Which of the following might a cement mason or concrete finisher be responsible for? (Select all that apply). repairing a cracked sidewalk
repairing a cracked sidewalk

creating the skeleton of a building
creating the skeleton of a building

constructing molds for pouring a foundation
constructing molds for pouring a foundation

monitoring the chemical reactions involved in hardening

Tom is having a problem with his washing machine. he notices that the machine vibrates violently at a frequency of 1500 rpm due to an unknown rotating unbalance. the machine is mounted on 4 springs each having a stiffness of 10 kn/m. tom wishes to add an undamped vibration absorber attached by a spring under the machine the machine working frequency ranges between 800 rpm to 2000 rpm and its total mass while loaded is assumed to be 80 kg a) what should be the mass of the absorber added to the machine so that the natural frequency falls outside the working range? b) after a first trial of an absorber using a mass of 35 kg, the amplitude of the oscillation was found to be 10 cm. what is the value of the rotating unbalance? c) using me-3.5 kg. m, find the optimal absorber (by minimizing its mass). what would be the amplitude of the oscillation of the absorber?

Apiping systems consists of 6 m of 6-std type k and 12 m of 4-std type k, both drawn copper tubing. the system conveys ethylene glycol at a rate of 0.013 m3/s. the pressure drop across the system is to be calculated. there are two 90° elbows in the 6-in pipe, a reduction from the 6-in pipe to the 4-in pipe and four 90° elbows in the 4-in pipe. all fittings are soldered (same as flanged) and regular. the inlet and outlet of the system are at the same height.

Aparticle moves along a straight line such that its acceleration is a=(4t^2-2) m/s, where t is in seconds. when t = 0, the particle is located 2 m to the left of the origin, and when t = 2, it is 20 m to the left of the origin. determine the position of the particle when t=4s.