Object Thrown Upward: Max Momentum & Equilibrium

AI Thread Summary
An object thrown upward reaches its maximum height with a velocity of zero, indicating that it has no momentum at that point. While the acceleration due to gravity remains constant at 9.8 m/s², this does not equate to equilibrium, as the net force is still the force of gravity acting downward. The object is not in mechanical equilibrium since the sum of forces is not zero; gravity is the only force acting on it. Kinetic energy is also not at its maximum at the top, as potential energy is maximized instead. Therefore, the correct answer to the original question is (e) none of the above.
garva1
Messages
17
Reaction score
0
an object is thrown upwards, at the top of the path it has
a) zero acceleration
b) maximum momentum
c) maximum kE
d) is at equillibrium
e)none of the above


i know accelarion is 9.8m/s^2
i also know is not KE since at the top is potential
im confused of the other two
 
Physics news on Phys.org
garva1 said:
an object is thrown upwards, at the top of the path it has
a) zero acceleration
b) maximum momentum
c) maximum kE
d) is at equillibrium
e)none of the abovei know accelarion is 9.8m/s^2
i also know is not KE since at the top is potential
im confused of the other two

b) what is formula for momentum?
d) what is equilibrium?
 
those are the ones that i don't know i think momentum is = mv
 
Ok, so if you know that P = mv, and the object is at the max height of its trajectory, then what would be it's velocity and momentum?
 
v is zero
 
ok vo is zero but the final velocity =v + gt but I am confused
 
yes, v=0 at the top, so what is the momentum at the top?
 
0 but what about equllibrium
 
look up the definition of mechanical equilibrium
 
  • #10
i don't get the definition is says something about rest but so does the free fall at top have equllibrium but then we only have one force gravity since air is neglected
 
  • #11
garva1 said:
i don't get the definition is says something about rest but so does the free fall at top have equllibrium but then we only have one force gravity since air is neglected

OK. Is it at rest at the top?
 
  • #12
http://en.wikipedia.org/wiki/Mechanical_equilibrium"

"A rigid body is in mechanical equilibrium when the sum of all forces on all particles of the system is zero, and also the sum of all torques on all particles of the system is zero."

What forces are at play here? Is the net force on the particle zero at the top of its path?
 
Last edited by a moderator:
  • #13
there is only gravity
 
  • #14
i don't get equllibrium sorry :(
 
  • #15
Ok, try and think fundamentally. At the very top, the instantaneous velocity is zero. If the velocity is zero then the net acceleration must also be zero at that very instant. So if F = ma, then the net force must be zero too. If you are still confused, I frankly do not know how else to explain it.
 
  • #16
so at the top there is equllibrium even though there is only one force the sum will be concidered zero
 
  • #17
"If the velocity is zero then the net acceleration must also be zero at that very instant. So if F = ma,"
but how does velocity applied in the equation f=ma
 
  • #18
but i thought that the acceleration was gravity and gravity was throughout the whole path
 
  • #19
chislam said:
Ok, try and think fundamentally. At the very top, the instantaneous velocity is zero. If the velocity is zero then the net acceleration must also be zero at that very instant. So if F = ma, then the net force must be zero too. If you are still confused, I frankly do not know how else to explain it.

That's incorrect, the velocity will be zero, but it will still be accelerating downwards; the net force will still just be the force due to gravity, which is nonzero.
 
  • #20
garva1 said:
but i thought that the acceleration was gravity and gravity was throughout the whole path

This thought is correct; see above^^^.
 
  • #21
but i thought the a was gravity and top gravity still 9.8
 
  • #22
so there is no equillibrium nor momentum nor kinetic energy and the acceleration is 9.8
 
  • #23
garva1 said:
so there is no equillibrium nor momentum nor kinetic energy and the acceleration is 9.8

Correct, so the answer is (e) none of the above.
 
  • #24
yayy THANK YOU VERY MUCH I am really thankfull so no do i just leave the thread open or there is a way to close it
THANK YOU
 
  • #25
Just leave the thread, so others may benefit from the discussion.
 
  • #26
Thank you
 
Back
Top