The Student Room Group

Terminal velocity?

Excuse me ,but (When a skydiver steps out of the plane)
1) Why would velocity be the greatest when it reaches its first terminal velocity?

Isn’t weight equal to the air resistance at this time ? So the resultant force(velocity) will be zero, and the person should stop moving.

2) And so it won’t have to open up his parachute?

3) Why would the second terminal velocity be smaller than the first one?

Thank you !
(edited 1 year ago)
Original post by Nancy2000
Excuse me ,but (When a skydiver steps out of the plane)
1) Why would velocity be the greatest when it reaches its first terminal velocity?

Isn’t weight equal to the air resistance at this time ? So the resultant force(velocity) will be zero, and the person should stop moving.

2) And so it won’t have to open up his parachute?

3) Why would the second terminal velocity be smaller than the first one?

Thank you !


Good morning! I am an early bird - actually a v early one - I get up at 5 a.m. every day incl Sunday, BUT YOU WERE UP AT 4 a.m. looks like :colondollar: - r u OK?


1) Cos the acceleration will be positive as soon as he/she jumps out = accel-n due to gravity MINUS deceleration due to air resis-ce [downward at 9.1 ms^-2 MINUS [upward] at x ms^-2] SO HE#SHE WILL BE ACCELERATING ALL THE TIME UNTIL acc-n due to gravity EQUALS dec-n due to air res-ce, yeah? This will be the first terminal vel = no more change in velocity i.e. steady velocity [max]. Still c me?

2) Sorry - Don't understand ur Q! [who is "it"?]

3) The 2nd term vel will be when he/she lands on the ground = equals WHEN VELOCITY IS ZERO, agreed? Oc zero is less than any positive no so less than 1st term vel.

I hope this answers [part of] your Q! Are u cooking some egg, bacon & sausages r n? YUMMY!! :yum: Am I invited or will I need to gate-crash lol :colondollar:?

Have a great day & be safe!

M
Reply 2
Original post by macpatgh-Sheldon
Good morning! I am an early bird - actually a v early one - I get up at 5 a.m. every day incl Sunday, BUT YOU WERE UP AT 4 a.m. looks like :colondollar: - r u OK?


1) Cos the acceleration will be positive as soon as he/she jumps out = accel-n due to gravity MINUS deceleration due to air resis-ce [downward at 9.1 ms^-2 MINUS [upward] at x ms^-2] SO HE#SHE WILL BE ACCELERATING ALL THE TIME UNTIL acc-n due to gravity EQUALS dec-n due to air res-ce, yeah? This will be the first terminal vel = no more change in velocity i.e. steady velocity [max]. Still c me?

2) Sorry - Don't understand ur Q! [who is "it"?]

3) The 2nd term vel will be when he/she lands on the ground = equals WHEN VELOCITY IS ZERO, agreed? Oc zero is less than any positive no so less than 1st term vel.

I hope this answers [part of] your Q! Are u cooking some egg, bacon & sausages r n? YUMMY!! :yum: Am I invited or will I need to gate-crash lol :colondollar:?

Have a great day & be safe!

M

Good morning!
Thank you for answering! I suppose we both are early birds then ! Nice to meet you !
Sorry, the “it refers to the skydiver .
I think I have got it .
I also found it easier to understand when you draw up a velocity time graph.( sorry for my bad drawing)
Like this .
image.jpg

Excuse me , but still have a question:
Is the velocity constant when the resultant force is 0 ?

I also looked up at newton’s 1st law that - A resultant force is required to change the motion of an object.
So the object will stay the same at its original motion .

For example : 1) Stationary 2)Move at its original speed /velocity

Second quest:
If the object starts at accelerating to the right , and then another force join in to let it decelerate, then will we regard its resultant force to be 0 at the first stage,and the other force that changes its motion (the force that let this object decelerate to the right ) be the resultant force ?

I.e. Can an object have several resultant forces in opposite directions? (Horizontally or verticality)
Or only one ,since According to the law, non zero resultant force will cause the force to accelerate, so to my understanding the first stage should have a resultant force too .

Of course, I would like to invite you😝 ( But do hesitate before you decide to come, I am a bad chef)😂

Wish you a good day too !

N
(edited 1 year ago)
Could not help noticing/laughing at your typo near end:- are you a "bad chief" of the Maumau tribe [cannibals] in Kenya where I was born lol [we had to watch out as kids not be eaten NOT ONLY by a lion/cheetah but ALSO by a Maumau hunter with a sharp spear lol [actually it is not funny cos it was real!!]

OR:

Are u a "bad chef" as in Jamie X [slim guy - forgot surname] or Gino or Ainsley Harriott??

:lol::lol::lol:

DW give me some time to answer this Q [have a job deadline today] - watch this space.

Thank you!
Reply 4
Sorry, I typed that wrong
I meant chef
But thanks for sharing your story !
You were born in Kenya?! Wow!
Of course,take your time
(edited 1 year ago)

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