You stretch a spring by a distance of 0.3 m. The spring has a spring constant of 440 N/m. When you release the spring, it snaps back. What is the kinetic energy of the spring as it reaches its natural length?
A.5.94 J
B.8.22 J
C.21.5 J
D.19.8 J

Question

You stretch a spring by a distance of 0.3 m. The spring has a spring constant of 440 N/m. When you release the spring, it snaps back. What is the kinetic energy of the spring as it reaches its natural length?
A.5.94 J
B.8.22 J 
C.21.5 J
D.19.8 J

anonymous · Answer

what about this one @LastDayWork

jfraser · Answer

what's the formula for the kinetic energy in a spring?

anonymous · Answer

I don't know...

jfraser · Answer

you've got to have some kind of info about springs, like from a textbook?

anonymous · Answer

i dont think so... we don't have a book

jfraser · Answer

no documents? notes? handouts? i think its fascinating that you're learning about springs with no resources or formulas

anonymous · Answer

yes it is.. do youknow a formula i can use?

jfraser · Answer

Just like a pendulum swings back and forth between potential and kinetic energy, the energy transformation in a spring oscillates between all potential (at its most compressed) to all kinetic (at its resting point), but the TOTAL energy in the spring must remain constant.

The kinetic energy the spring has at its resting position must be equal to the total potential energy given to the spring when it was compressed to begin with. The formula for PE in a spring is:
$$PE_s = \frac {1}{2} kx^2$$where k is the spring constant, and x is the displacement from the resting position

anonymous · Answer

so D will be the answer, thanks