Question

a. Initially, before the engine is ignited, the rocket sits at rest on top of the spring. How much is the spring compressed?

b. After the engine is ignited, what is the rocket's speed when the spring has stretched 30.0 cm?

c. For comparison, what would be the rocket's speed after traveling this distance if it weren't attached to the spring?

Answer 1

a) conserving energy,
10.5*9.8*x = .5*450*x^2
so, x = 0.457 m <----compression

b) conserving energy,

.5*450*.457^2 = .5*450*.3^2 + 10.5*9.8*(.3+.457) + .5*10.5*v^2
so, v= 1.89 m/s <----answer

c)450*.3 = 10.5*9.8*.3* + .5*10.5*v^2
so, v = 4.45 m/s <----answer