Block move down the curved hill and hit attached block spring with diagram

cecico

A 100grams block is moving at 2m/s down the curved hill. The block slides along the smooth surface and collides elastically with the 400gram block. The 400gram block is initially at rest and is attached to an ideal spring with spring constant of 500N/m
a)Find the maximum distance the spring compresses
b)Find the maximum height the 100gram block reaches after the collision.

I added a diagram....... help me T.T

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cecico

oh~ height is 3.0m.......

tiny-tim

Hi cecico! Welcome to PF!
I don't understand … it will be accelerating … at which point is its speed 2m/s?

DavidWhitbeck

Someone else asked this exact same question on another thread, and that poster made the same mistake you did-- you have not attempted the problem. You must show that you have worked on the problem before asking for help.

Saladsamurai

Not someone else.

To start you off. I would ask my self what theory(s) I would like to apply to solve this problem. What theories have you learned that involve finding velocities and displacements?

Work-Energy theorem and Conservation of Energy come to mind. Which would be easier in this case?

And this too. Where is its velocity 2 m/s ?

DavidWhitbeck

Oh you're right SaladSamurai! That poster must be impatient.

cecico

SaladSamurai your right........ I have to use Work-Energy theorem and Conservation of Energy and the speed is 2m/s at point A and the surface is smooth.......

tiny-tim

Hi cecico!

ok … then what is the speed of the 100grams block just before it hits the other block?

cecico

according to my calculation I got 7.925m/s.........after this i have no idea.....

tiny-tim

That's right.

Now pretend that there's no spring, and work out the speeds of the two blocks immediately after the collision.

cecico

immediately after the collision I got 1.585m/s.... is this right??????????

tiny-tim

uuh? you should get two speeds … one for each block!

(and if you show your working, that'll save me time checking! )

cecico

ok......now i really don't get it..... what equation do i have use??
momentum equation???? Mv+Mv=Mv+Mv but theres two unknown.....
how do i calculate this????????? -0-

tiny-tim

Hi cecico!

(i can tell you're panicking because the number of question marks is increasing faster than exponentially!!)

In collisions, momentum is always conserved.

And you're told that this collision is elastic, and that means that energy is also conserved.

Two equations … two unknowns … physicist's heaven!

cecico

alright for 100gram I got -4.755m/s and for 400gram I got 3.17m/s......it seems wrong..T.T

tiny-tim

Well, let's assume it's right.

You now have an initial velocity for the 400gram block.

So … what is the maximum distance the spring compresses?

cecico

I got 0.08966m........