homework help > physics > physics q&a board > topic: work and energy...

Q BgQuestion:

      
Novice
Karma Points: 35
Respect (96%):
posted by  AndrewMM on 11/4/2009 10:10:25 PM  |  status: Closed  |  Earned Karma: 35

work and energy

Course Textbook Chapter Problem Needs by
Calculus Based Physics instructor given problem work and energy N/A 11/5/2009 at 11:00:00 PM
Question Details:
These are review questions for a test that I am having problems with, please help!
1. A force of ten newtons holds an ideal spring with a 20 N/m spring constant in compression. the potential energy stored in the spring is?
2. At one instant of time a rocket is travelling in outer space at 2500 m/s and is exhausting fuel at a rate of 100 kg/s. If speed of fuel as it leaves the rocket is 1500 m/s relative to the rocket the thrust is?
Andrew M EE Student
Bonus Point Alert! Earn +4 additional karma points for helping this gold member.

AAnswers:

Answer Question Ask for clarification
Scholar
Karma Points: 269
posted by jacksparrow on 11/4/2009 10:54:08 PM  |  status: Live
Asker's Rating: Lifesaver   
Response Details:
F = kx
10 = 20x
x = 0.5 m

PE = 0.5 * k * x2

PE = 0.5 * 20 * (0.5)2

PE = 2.5 J

Remember thrust is just a force

F = ma
You can rearrange the info you have to get m and a.
(100 kg/s) * (1500 m/s)
(100 kg) * (1500 m/s2)
F = (100 kg) * (1500 m/s2)
F = 150000 N
Answer Question Ask for clarificarion
Ask New Question

Join Cramster's Community

Cramster.com brings together students, educators and subject enthusiasts in an online study community. With around-the-clock expert help and a community of over 100,000 knowledgeable members, you can find the help you need, whenever you need it. Join for free today » How Cramster is different from tutoring »

Need Help In

Useful Links