Hello out there!
I am totally stumped on a homework problem and need a hand figuring it out. Can anyone please look at this problem and help me solve it? here is the problem.
A 2.00kg projectile is fired vertically upward with an initial velocity of 98.0 m/s. Find its kinetic energy, its potential energy, and the sum of its kinetic and potential energies at each of the following times:
a.)the instant of its being fired.
b.)t=1.00 seconds
c.)t=2.00 seconds
I really would appreciate anyone's help, thank you!
ok, I'm going to go with the philosophy of my physics professor, I won't show you how to do it, but I'm going to do my best to guide you.
a) what's the equation for kinetic energy? what's the equation for potential energy? that's all you need to solve this.
b&c) all you need to do here is find the velocity at these various times for kinetic
energy, and find the height for potential. Look at the kinematic equations.
as far as the sum of the kinetic and potential energies and any given time.
Remember conservation of energy...energy in, cannot exceed energy out..this is for an ideal situation...i assume you are dealing with an ideal situation here. Meaning no friction, or negligible anyway. Anyway, I hope this has been some help.
a) what's the equation for kinetic energy? what's the equation for potential energy? that's all you need to solve this.
b&c) all you need to do here is find the velocity at these various times for kinetic
energy, and find the height for potential. Look at the kinematic equations.
as far as the sum of the kinetic and potential energies and any given time.
Remember conservation of energy...energy in, cannot exceed energy out..this is for an ideal situation...i assume you are dealing with an ideal situation here. Meaning no friction, or negligible anyway. Anyway, I hope this has been some help.
Hello,
And thanks for responding to my post. If I understand you correctly then, to solve for KE all I do is multiply 1/2mv squared. which would be .50*2.00kg*98m/s squared? My answer to that is 9604. Am I getting that right?
And thanks for responding to my post. If I understand you correctly then, to solve for KE all I do is multiply 1/2mv squared. which would be .50*2.00kg*98m/s squared? My answer to that is 9604. Am I getting that right?
hey man, i will help you out with the "sums" portion.... conservation of mechanical energy states that mechanical energy is conserved in such a problem.... mechanical energy is the sum of all kinetic and potential energies involved.... so whatever the kinetic energy is initially will be the total amount of energy in the system at all times... this also means that if you find one of the energies at the end of each time period you can subtract from the intial energy to find the other energy...
Thank you very much for your help gentlemen!
QUOTE
a.)the instant of its being fired.
b.)t=1.00 seconds
c.)t=2.00 seconds
answer:
a ) 9604 J (which is the total i.e. K.E. + P.E.)
b ) K.E. = 7779.24 J
P.E. = 1824.76 J (Total - K.E. to save using the displacement eq.)
c ) K.E. = 6146.56 J
P.E. = 3457.44 J (Total - K.E.)
We used to like a good projectile question in exams, plenty of marks for using common sence.
QUOTE (bonesmccoy+Jul 20 2005, 07:54 PM)
Hello,
And thanks for responding to my post. If I understand you correctly then, to solve for KE all I do is multiply 1/2mv squared. which would be .50*2.00kg*98m/s squared? My answer to that is 9604. Am I getting that right?
you got it.
And thanks for responding to my post. If I understand you correctly then, to solve for KE all I do is multiply 1/2mv squared. which would be .50*2.00kg*98m/s squared? My answer to that is 9604. Am I getting that right?
you got it.
And this is the basis for ballistic trajectory calculations - instead of going straight up the projectile is fired at an angle and gravity is acting to return the projectile downwards.
As Professor Andy says, there are regularly many marks available for standard calculations - if you faliliarise yourself with these equations and situations you will get a head start when you get such an exam question.
Best of luck with it.
As Professor Andy says, there are regularly many marks available for standard calculations - if you faliliarise yourself with these equations and situations you will get a head start when you get such an exam question.
Best of luck with it.
1. A guitar string is plucked and it undergoes SHM. Describe a single oscillation by considering the string's mass, momentum and restoring force??
2. A pendulum has a bob of mass 240g and is displaced by an angle of 8 degrees from the vertical position. Calculate the restoring force on the pendulum??
2. A pendulum has a bob of mass 240g and is displaced by an angle of 8 degrees from the vertical position. Calculate the restoring force on the pendulum??
Hi Phoebe62!
You'd better make a new post, as this subject isn't related to the former one.
See you there.
You'd better make a new post, as this subject isn't related to the former one.
See you there.
nvm
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