Projectile Motion : Work and Energy

[ReCryptic]

Homework Statement

Estimate the amount of work done on the ball by the spring.

Relevant Equations

Work for spring = -1/2kxf^2 + 1/2kxi^2
Kinetic Energy = 1/2mv^2
Potential Spring Energy = 1/2kx^2

The problem is based on a projectile-spring launcher. A ball is loaded into a tube that pushes back a spring and is then launched. The ball was launched straight horizontally not at an angle.

I'm trying to find the work done on the ball by the spring.

The info I have:

Displacement of spring = .05m
Mass of ball = .010kg
Initial height = 0m.
Initial velocity of ball after launch = 2 m/s.

KE = 1/2mv^2
= 1/2 * .01kg * 2m/s^2 = .2J

The spring energy is converted to Kinetic energy after launch so KE = Uspring.

KE = Uspring
.2J = 1/2kx^2
.2J = 1/2k*(.05m)^2
80 = 1/2k
k = 160 N/m.

Is my work so far correct?

 

[NascentOxygen]

1/2 * .01kg * 2m/s^2 = .2J

Is the decimal point misplaced?

 

[ReCryptic]

Which one?

 

[ReCryptic]

I figured it out can you delete the post please?

 

[NascentOxygen]

I figured it out can you delete the post please?

On PF, once a post has received help, the thread is never* deleted.

* almost never