Posted by **Lilly** on Monday, March 5, 2012 at 12:40am.

Two blocks, each with a mass = 0.168 kg, can slide without friction on a horizontal surface. Initially, block 1 is in motion with a speed = 1.28 m/s; block 2 is at rest. When block 1 collides with block 2, a spring bumper on block 1 is compressed. Maximum compression of the spring occurs when the two blocks move with the same speed, /2 = 0.640 m/s. If the maximum compression of the spring is 1.55 cm, what is its force constant?

- Physics -
**drwls**, Monday, March 5, 2012 at 12:59am
At maximum compression, the spring potential energy will equal the drop in Total kinetic energy. Total KE goes from (M/2)Vo^2 to 2*(M/2)*(Vo/2)^2

= (M/4)Vo^2/4

M is the mass of one block; Vo is its initial speed of block 1

(M/2)Vo^2/4 = (k/2)X^2

Solve for k

- Physics -
**Lilly**, Monday, March 5, 2012 at 1:39am
Im still confused. Ive tried solving for k a couple of different ways and the website tells me that I am wrong. My answers have ranged from .0286 to 791.1 N/m. Ive tried converting 1.55 cm to m, and it still says that I am wrong.

- Physics -
**drwls**, Monday, March 5, 2012 at 3:40am
X = 1.55*10^-2 m

M = 0.168 kg

Vo = 1.28 m/s

k = (Vo/X)^2*M = 1146 N/m

You apparently did not use the formula I provided.

## Answer this Question

## Related Questions

physics - Two blocks, each with a mass m = 0.400 kg, can slide without friction ...

physics - An m=150 g block hits an M= 265 g block initially at rest on a ...

Physics - Two blocks, stacked one on top of the other, slide on a frictionless ...

Physics - Two blocks, stacked one on top of the other, slide on a frictionless ...

physics - The coefficient of static friction is 0.604 between two blocks. The ...

Physics - A 23.0 kg block is initially at rest on a horizontal surface. A ...

physics - A 20kg block is initially at rest on a rough, horizontal surface. A ...

Physics - A block of mass m = 2.00 kg rests on the left edge of a block of mass ...

Physics - A bullet with a mass m=12.5 g and speed v=85.4 m/s is fired into a ...

Physics - A block of wood of mass 1.2kg initially at rest is free to slide on a ...