An unknown material, with a mass of 54 gm, was submerged in water. the object occupied 14 gm of water. what is the density of the material?

Density of unknown material = 3.86 g/cm³

Explanation:

Mass of unknown material, M = 54 gm

The object occupied 14 gm of water.

Volume of unknown material = Volume of 14 gm of water.

Density of water = 1 gm/cm³

Volume of 14 gm of water  

Volume of unknown material, V = Volume of 14 gm of water = 14 cm³

Density of unknown material    

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.