Q. 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?

Q. An ammeter of resistance R is connected through a rheostat to a cell of a negligible internal resistance. When the rheostat is adjusted to a value R1, the ammeter reads 0.75 of the full-scale value. When it adjusted to a value R2, the ammeter reads 0.25 of full-scale value. Compute the value of Ra in terms of R1 and R2.