A steel ball of 20 mm diameter (k = 60 W/m·ºC, α = 177×10-6 m2/s, rho = 7854 kg/m3) is dropped in a large tank of water. The sphere ball is initially isothermal at 360 K and drops until the center temperature is 320 K, and the temperature of the water is 280 K. The sphere ball may be assumed to quickly reach the terminal velocity of 1.3 m/s in the water. Determine the height of the water tank required to cool the sphere ball to 320 K. Use analytical one-term approximation method for the conduction heat transfer.

If you were designing a bumper for a car, would you prefer it to exhibit elastic or plastic deformation? why? consider the functions of a bumper in both a minor "fender-bender" and a major collision.

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.

Apure substance is a)-mixture of various chemical elements or compounds b)-substance that has a fixed chemical composition throughout c)-mixture that is homogeneous (such as air) d)-all the answers