Calculating Block Speed Before Compressing Spring

[joshbrackeen]

1. A 4020 gram block slides on a frictionless surface into a spring and compresses it 3.70 cm before the block briefly comes to rest. The spring constant is 2500 N/m. Calculate the speed of the block just before it compresses the spring.



2. KE=1/2mv^2 and U_s=1/2kx^2



3. KE = U_s
2010v^2=1.71
v=0.0292 m/s

My professor received a different speed in her answer so I was wondering if I did something wrong.

 

[PhanthomJay]

You've got to watch units and algebra. Convert grams to kg and cm to meters before solving, and try again. Your units must be consistent.