SOLUTION: Hi guys, the last question I put up had such a fantastic response, it'd be great if you could help me out with one more. Word problems really confuse me. The energy in Joules

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Hi guys, the last question I put up had such a fantastic response, it'd be great if you could help me out with one more. Word problems really confuse me. The energy in Joules       Log On


   



Question 683725: Hi guys, the last question I put up had such a fantastic response, it'd be great if you could help me out with one more. Word problems really confuse me.

The energy in Joules (j) of a particle varies directly with the square of it's speed, in m s ^-1. A particle moving at 20 m s ^-1 has 50J of energy.
a) How much energy has a paricle moving at 4ms^-1?
b) At what speeed is a particle moving if it has 200J of energy?

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
If it's a direct variation, I can say
+20+%2F+50+ ( m/s ) / J is a constant
(a)
+2%2F5+=+4%2FE+
+2E+=+20+
+E+=+10+ J
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(b)
+2%2F5+=+s+%2F+200+
+400+=+5s+
+s+=+80+ m/sec