What is the ball's maximum acceleration?

[lijoeman]

Homework Statement

A 160 g ball attached to a spring with spring constant 2.8 N/m oscillates horizontally on a frictionless table. Its velocity is 20 cm/s when x_0 = 4.5 cm.

a_max = _______ cm/s^2


2. The attempt at a solution

Using F = ma and F = kx
kx = ma
a = kx/m

Substituting the appropriate values

a = (2.8)(4.5)/(.16) = 78.75 cm/s^2

Am I missing something here?

 

[CaptainEvil]

Homework Statement

A 160 g ball attached to a spring with spring constant 2.8 N/m oscillates horizontally on a frictionless table. Its velocity is 20 cm/s when x_0 = 4.5 cm.

a_max = _______ cm/s^2


2. The attempt at a solution

Using F = ma and F = kx
kx = ma
a = kx/m

Substituting the appropriate values

a = (2.8)(4.5)/(.16) = 78.75 cm/s^2

Am I missing something here?

check your units. your spring constant is in N/m, while you're speed is in cm/s

 

[Doc Al]

Using F = ma and F = kx
kx = ma
a = kx/m

That gives you the acceleration at some particular value of x. It will only be a_max when x = x_max.

How can you find the maximum value of x? Hint: Make use of the speed that was given.