Quartz has a density of 2.2 g/cm. You have a sample with a volume of 45 cm. What is its mass?
20.45 g

99 g

45 g

0.05 g

The boy of mass 30 kg is at r1= 2 meters from the fulcrum. of the girl is 45 kg, at what r2 must she sit so that they are balanced ?

Matter is needed to transfer thermal energy bya. conductionb. convectionc. radiation d. both a & b.

An object with initial temperature 130 ∘ f is submerged in large tank of water whose temperature is 50 ∘ f . find a formula for f ( t ) , the temperature of the object after t minutes, if the cooling constant is k = − 0.2 . remember newton's law of cooling (the rate of change of temperature with respect to time is equal to k times the difference between the temperature of the object and the surrounding temperature) ! : )