Ahorizontal spring with spring constant 85 n/m extends outward from a wall just above floor level. a 9.5 kg box sliding across a frictionless floor hits the end of the spring and compresses it 6.5 cm before the spring expands and shoots the box back out. how fast was the box going when it hit the spring?

Spring constant: 85N/m, 9.5kg box, compresses spring 0.035m. 

85N/m* 0.035m = 2.975N 

Use spring equation 1/2*k*(change in distance) ^ 2 

1/2*85N/m*(0.035m) ^ 2=0.052063J 

Now use kinetic equation:

1/2*m*v^2 
0.052063J=0.5*9.5kg*v^2 
v = 0.1047 m/s

well, you would divide 135 by 33 to get your answer. then that is how many seconds it would take. boardman should fly about 132 m or 4.090909090909091 seconds.