Question

#7

6. Estimate the angular acceleration of the wheels on your car in a typical start from zero to 30 m/s. This does not mean some wild, unjustified number of radians/s2. It does mean making at least two numerical estimates and using them in at least 3 equations, all of which must be shown to get credit on this one. If you need some hints, check the Discussion section on Canvas 7. The maximum pressure Portland cement concrete can withstand under compression ranges between 20 and 40 megaPascals (3 000 to 6 000 psi). (This value is known as the maximum stress and it increases as the concrete ages.) Its density is about 2 300 kg/m2. How tall a column of concrete could you build before it failed at the base?

Answer 1

As the pressure at the base of concrete will be P =rho*g*h

h = P/(rho*g) will be the maximum height

Taking 20 MPa to be in safe range

h = 20*10^6/(2300*9.81) = 886.40 metres (due to its own weight)

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