Final answer:
The initial speed of the cannonball is 15 m/s.(Option 4)
Step-by-step explanation:
To find the initial speed of the cannonball, we can use the formula for potential energy stored in a spring: PE =
, where PE is the potential energy, k is the spring constant, and x is the compression distance. We can set the potential energy equal to the kinetic energy of the cannonball when it is released from the spring:
, where m is the mass of the cannonball and v is its velocity. We can solve for v by equating and rearranging the equations:


Plugging in the given values of k = 1800 N/m, x = 0.55 m, and m = 7.0 kg, we get:
v =
= 15 m/s
Therefore, the initial speed of the cannonball is 15 m/s (Option 4).