Calculating Speed of Ball Leaving Spring Gun

[mikefitz]

A spring gun (k = 28 N/m) is used to shoot a 56-g ball horizontally. Initially the spring is compressed by 18 cm. The ball loses contact with the spring and leaves the gun when the spring is still compressed by 12 cm. What is the speed of the ball when it hits the ground, 1.4 m below the spring gun?

I calculated Vi = sqrt((28*6^2)/56)) = 4.24264 m/s

Since the horizontal velocity component is independent of the vertical component doesn't the x velocity remain at 4.24 m/s?

 

[007banshee]

Yes x velocity is constant unless acted upon by air resistance or something.

 

[mikefitz]

Yes x velocity is constant unless acted upon by air resistance or something.

Then why does the book insist my calculated answer is incorrect?

 

[drpizza]

Yes, horizontal velocity remains constant. The problem didn't ask for the horizontal component of the velocity.

(hint)