A hot plane surface at 100°C is exposed to air at 25°C with a combined heat transfer coefficient of 20W/m2*K The heat loss from the surface is to be reduced by half by covering it with sufficient insulation with a thermal conductivity of 0.1 W/m*K. Assuming the heat transfer coefficient to remain constant, the required thickness of insulation is

(a) 0.1cm
(b) 0.5 cm
(c) 1.0 cm
(d) 2.0 cm
(e) 5 cm

The temperature at a point (x, y) is t(x, y), measured in degrees celsius. a bug crawls so that its position after t seconds is given by x = 6 + t , y = 8 + 1 3 t, where x and y are measured in centimeters. the temperature function satisfies tx(3, 9) = 5 and ty(3, 9) = 4. how fast is the temperature rising on the bug's path after 3 seconds? (round your answer to two decimal places.)

Aballoon is rising vertically upwards at a velocity of 10m/s. when it is at a height of 45m from the ground, a parachute bails out from it. after 3s he opens his parachute and decelerates ata a constant rate 5m/s. when. (a) what was the height of the parachutist above the ground when he opened his parachute? (b)how far is the parachutist from the balloon at t=3s? (c)with what velocity does the parachutist hit the ground? (d)after how long does the parachutist hit the ground after his exist from the balloon?

Why do some scientists and archeologists think that volta was not the first person to build a battery