Conservation of Energy

  • #1
A block, mass 0.75 kg, is "shot" from a spring gun from a table. The table has a height 1.04 m and is frictionless. If the spring has k=28 N/m and is originally compressed 0.23 m, how fast will the block be goign when it hits the ground?

(1/2)*kx^2 = (1/2)mv^2 ?

I got 4.3 m/s but the answer is 4.73 m/s
  • #2
If you show us your work, we can say where you've gone wrong.
  • #3
(23*0.23^2)/2= (0.75*9.8*1.04)+(0.7*v^2)/2
  • #4
Hint: you have to "count in" the height of the table somehow in your calculation.
  • #5
(23*0.23^2)/2= (0.75*9.8*1.04)+(0.7*v^2)/2
Are you sure?? You need to find the velocity at the bottom and not at 1.04m. Also, k = 28N/m, not 23.

Suggested for: Conservation of Energy