Question

Does air resistance affect the motion of a falling object differently when the mass is greater? Explain

Answer 1

Mass and weight,gravitational pull on an object, are directly proportional. Twice the mass = twice the weight, in the same location. So if there is a greater mass an object will fall faster. Mass is not proportional to volume. A pillow has more volume than a small weight but has less mass. Air resistance relies on surface area, so the greater the volume of an object the more air resistance. So mass will not increase or decrease air resistance, volume and surface area will. Its like dropping the pillow and the weight, except the the pillow has the same mass as the weight, the pillow will fall a bit slower due to more air resistance, by its surface area and volume. HOPE THIS HELPS

Answer 2

If it has a greater mass then it will only cause it to go faster because it will possess a greater weight. A greater weight means that it will have more force to counteract the force of the air resistance.
If there would be no air resistance then all objects of the same volume would fall at the same time because their gravitational accelerations would be constant.

Answer 3

*So if there is a greater mass an object will fall faster.*

that is absolutely not true. leaving aside air resistance, everything will fall at the same rate of acceleration. this is why Neil Armstrong dropped a feather on the moon. (virtually) no atmosphere so it hit the ground at the same time as a rock dropped from the same height at the same time.

now turn on the air resistance, eg go back to the surface of the earth, and assume (1) a normal feather and (2) an exactly similar feather except it is made of lead, both dropped at the same time and with the same orientation.

each will accelerate initially at 9.8m/s/s but each will begin to lose momentum (and energy) to the air particles on account of collisions with air particles - amnd so the question is by how much.

the amount of collisions will depend on the contact surface (the same for each feather) and also the rate at which the object is falling (initially, the same), which is why terminal velocity kicks in after a while - a faster object will have more collisions per unit time.

and the effect of air resistance follows from the way that the actual interchange of momentum (and energy) occurs. imagine now (1) a head on collision between 2 identical dinghies at sea as opposed to (B) a head on collision between an oil tanker and 1 dinghy. it is through the application of conservation of momentum that we know the oil tanker will plough through the dinghy (whereas the 2 dinghys might well collide and coalesce, or bounce off each other).

similarly the oil tanker could slice through a flotilla of dinghies, just as the lead feather will slice more readily through the air, with no appreciable loss of velocity.

you can play with the momentum and energy equations and see this for yourself. i think it would be perfectly safe to model these as completely elastic.

it all comes back to Newton's 2nd (as originally formulated: F = dp/dt where p = mv) and 3rd laws.

Answer 4

My answer is correct

Answer 5

Alright thanks