An aluminum pan whose thermal conductivity is 237 w/m⋅k has a flat bottom with diameter 15 cm and thickness 0.4 cm. heat is transferred steadily to boiling water in the pan through its bottom at a rate of 800 w. if the inner surface of the bottom of the pan is at 100°c, determine the temperature of the outer surface of the bottom of the pan.

100.76 °C

Explanation:

Let T₁ be the temperature of outer surface. Area of surface

A = 3.14 x ( 15/2 )²x 10⁻⁴ m² = 176.625 x 10⁻⁴ m²

For thermal conduction through a metallic surface the equation is

Q is heat passed which is 800 J here , t is time which is 1 s here, K is coefficient of thermal conductivity which is 237 wm⁻¹  A is area , T₁ and T₂ temperature of two sides , T₂ is 100 ° C .

Putting the values

800 =

T₁ = 100.76 °C

b. lifting dumbbell weight at 20-degree angle from the body after a 45-degree angle

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg