By how much will the length of a chicago concrete walkway that is 18 m long contract when the equipment drops from 24 degrees celcius in july to (-16 degrees celcius) in janruary?

Contraction of Chicago concrete walkway = 8.64 x 10⁻³ m

Explanation:

Thermal expansion or compression is given by ΔL = LαΔT

Here Length of Chicago concrete walkway, L = 18 m

         Change in temperature, ΔT = (-16 - 24) = -40 °C

         Coefficient of thermal expansion for concrete, α = 12 x 10⁻⁶ °C⁻¹

Substituting

    ΔL = LαΔT = 18 x 12 x 10⁻⁶ x (-40) = -8.64 x 10⁻³ m

Contraction of Chicago concrete walkway = 8.64 x 10⁻³ m

Mechanical(ME) energy, in physical sciences, is the sum of kinetic energy (KE) and potential energy (PE). Below are the calculation in obtaining the energies,
 
     (1) KE =   0.5mv²     =  0.5(0.1 kg) x (2 m/s)² = 0.2 J
     (2) PE =    md          = (0.1 kg) x (1.5 m)        = 0.15 J
      (3) ME =  KE + PE = 0.2 J + 0.15 J               = 0.35 J

Thus, the mechanical energy is 0.35 Joules.