As 390-g of hot milk cools in a mug, it transfers 30,000 j of heat to the environment.
how does the temperature of the milk change? (cmilk = 3.9 j/g°c)
a) it increases by 77°c.
b) it decreases by 77°c.
c) it increases by 20°c.
d) it decreases by 20°c.

Currents in dc transmission lines can be 100 a or higher. some people are concerned that the electromagnetic fields from such lines near their homes could pose health dangers. for a line that has current 150 a and a height of 8.0 m above the ground, what magnetic field does the line produce at ground level? express your answer in teslas and as a percentage of the earth’s magnetic field, which is 0.50 g. is this value cause for worry?

Anika asks eva to roll a basketball and then a bowling ball to her. which requires more force to roll, and why?

Awave has a wavelength of 7 mm and a frequency of 19 hertz. what is its speed?