# Physics

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1. A force F = (3.99xi + 2.86yj) N acts on an object as it moves in the x direction from the origin to x = 4.45 m. Calculate the work done on the object by the force.

Attemp:
since we only consider x direction i multiplied 3.99 by 4.45 but it didn't work out.

2. A 10.6 kg weather rocket generates a thrust of 226.0 N. The rocket, pointing upward, is clamped to the top of a vertical spring. The bottom of the spring, whose spring constant is 402.0 N/m, is anchored to the ground. Initially, before the engne is ignited, the rocket sits at rest on top of the spring.

A: After the engine is ignited, what is the rocket's speed when the spring has stretched 19.4 cm past its natural length?

B: What would be the rocket's speed after travelling the distance if it weren't tied down to the spring?

Attemp:
i used 1/2kx^2+Fthrust(d) = 1/skx^2 + mg(d) + 1/2mv^2 to solve (A) but i'm getting the wrong answer and i also used 3 other equations to solve this but they all wrong.
i have no idea how to start part (B)

Thank you

• Physics -

Thank You bobpursley.

• Physics -

I think i got it now.