Projectile Motion : Work and Energy

AI Thread Summary
The discussion focuses on calculating the work done on a ball by a spring in a projectile-spring launcher scenario. The user provided details including the spring's displacement, the ball's mass, and its initial velocity to derive the kinetic energy. They correctly calculated the kinetic energy as 0.2 J and equated it to the potential energy stored in the spring. The user then determined the spring constant to be 160 N/m. After resolving their confusion regarding a decimal point, they requested the deletion of their post, but were informed that such posts are rarely deleted on the forum.
ReCryptic
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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?
 
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ReCryptic said:
1/2 * .01kg * 2m/s^2 = .2J
Is the decimal point misplaced?
 
Which one?
 
I figured it out can you delete the post please?
 
ReCryptic said:
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
 
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