I am doing these questions, and I don't quite understand.(adsbygoogle = window.adsbygoogle || []).push({});

1. A marble spins in a verticle plane around the inside of a smooth, 20cm-diameter horizontal pipe. The marble's speed at the bottom of the circle is 3.0m/s

a) what is the marble's speed at the top?

b) Find an algebraic expression for hte marble's speed when it is at angle phata, where the angle is measured from the bottom of the circle.

For part a, I used

1/2mvf^2 + mgyf = 1/2 mvi^2 + mgyi

to find vf , and i got 2.25 m/s

But for part b, i don't understand where should I draw the angle.

2. A vertical spring with k = 490 N/m is standing on the ground. You are holding a 5.0kg block just above the spring, not quite touching it.

a) How far does the spring compress if you let go of the block suddendly?

b) How far does the spring compress if you slowly lower the block to the point where you can remove your hand without disturbing it?

c) Why are your two answers different?

How do I deal with questions with a vertical spring?

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# Homework Help: What is the marble's speed at the top?

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