You're lying on a towel, enjoying the sunshine. You decide to venture down to the water. Ouch, the sand is hot! You run to the water, where you cool your burning feet.

A. Why is the water cooler than the sand?

B. If the sand you ran across has a specific heat capacity of 835 J/(kg°C), how much energy must be added to a 2-kilogram pile of it to increase its temperature from 40°C to 50°C? Show your work.

Explanation:

A )

During sunshine , both water and sand receives heat from the sun . but the specific heat of water is more so increase in temperature is less in water . It can be understood with the help of following relation .

Q = m s ΔT

Q is heat added to mass m of an object having specific heat s . Rise in temperature is ΔT .

ΔT = Q / m s

If s is higher , ΔT will be less

That is why increase in temperature of sand is more because s is less for sand.

B )

Q = m s ΔT

s = 835 J /kg°C

m = 2 kg

ΔT = 50 - 40

10°C

Q = 2 x 835 x 10

= 16700 J .

Energy to be added

= 16700 J .

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .