Physics Question (O Levels)

• rollwith_thekoalas

  2 Aug 12, 23:49

  Hi i need help with the chapter on kinematics.

  I am a little confused by acceleration of free fall and terminal velocity. What actually affects the amount of time before an object reaches terminal velocity? Let's say i have two objects, same shape, same size but different mass. Both are released from the same height. Which one reaches terminal velocity first? (In the presence of air resistance)

  Thanks! :)

   

• eagle

  3 Aug 12, 00:40

  The object with a lower mass will reach terminal velocity first.

  Terminal velocity occurs when air resistance equals to the weight of the object. The object with a lower mass will thus achieve terminal velocity with a lower amount of air resistance.

  Since air resistance is proportional to velocity, this means that the terminal velocity of the object with lower mass is lesser.

  Since the velocity is lesser, therefore it takes a shorter amount of time to achieve the lesserterminal velocity.

• Dareenho

  3 Aug 12, 02:57

  Terminal velocity is achieved when  F=mg=w=Air resistance. Therefore, depending on the mass of object, considering g and air resistance are constant (same shape and size), the mass will be the only variable. So looking at the formula, higher the mass, the longer it takes to achieve terminal velocity 

• bycai

  3 Aug 12, 08:24

  will height of fall also a determinable cause for the effect of terminal velocity ?

• eagle

  4 Aug 12, 08:34

  Originally posted by bycai:

  will height of fall also a determinable cause for the effect of terminal velocity ?

  For the purpose of O levels, A levels, and probably first year uni physics, no.