In which of the following circumstances would the free fall model be most accurate? Your :
1) A rock is dropped from 1 m above the ground.
2) A rock is dropped from 100 m above the ground.
3) A balloon is dropped from 1 m above the ground. (This balloon is filled with normal air, not helium.)
4) A balloon is dropped from 100 m above the ground. (This balloon is filled with normal air, not helium.)

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?

The vapour pressure of benzene is 53.3 kpa at 60.6 °c, but it fell to 51.5 kpa when 19.0 g of a non-volatile organic compound was dissolved in 500 g of benzene. calculate the molar mass of the compound.

Refrigerant-134a flows through a carnot heat pump cycle at 0.5 kg/s. it is known that the maximum absolute temperature in the cycle is 1.1 times the minimum absolute temperature, and the net power input to the cycle is 2.5 kw. if the refrigerant changes from a saturated vapor to a saturated liquid during the heat rejection process, determine the maximum magnitude of the enthalpy of vaporization for this process in kj/kg (with 3 significant figures).