When a 85 kg man sits on the stool, by what percent does the length of the legs decrease? assume, for simplicity, that the stool's legs are vertical and that each bears the same load?

Find stress using the formula Stress = Force / Area. Here, force exerted by 85kg person on stool is F = mg = 85kg * 9.8 m/s^2 = 833N. Find total area of 3 legs A = 3 π (D/2)^2 = 3 π (2.5 x 10^-2 / 2)^2 = 1.4726 x 10^-3 m^2. Now substitute in Stress = Force/Area. Stress = 833N / 1.4726 x 10^-3 m^2 = 5.656 x 10^5 N/m^2. Find strain using the formula strain = Stress / Young’s modulus. For wood, Y = 1.3 x 10^10 N/m^2. Thus, strain = 5.656x10^5 N/m^2 / 1.3x10^10 N/m^2 = 4.35 x 10^-5 = 0.00435%. 

Therefore, the legs decrease by 0.00435%

carla slowed down in the beginning of her trip, stopped, and then sped up

  the unit of the measure =

explanation:

  the property that is quantified by the energy needed per of material to raise the temperature by one.

  si unit of energy = joule (j)

  si unit of temperature = kelvin (k)

  si unit of mass of material = kilogram (kg)

the property that is quantified by the energy needed per of material to raise the temperature by one is called specific heat.

the unit of specific heat is