hi there, i'm planning to take university physics in the fall, but i'm lousy at it and doing some practise problems in advance :( i was doing some loop problems, and i'm extremely confused and disheartened and was wondering if anyone could help me?(adsbygoogle = window.adsbygoogle || []).push({});

The set up is pretty simple:

- there is a ramp of height, H

- A block is released from H

- At the bottom of the ramp there is a loop with radius of 10m, and R<H

- The block is 1kg

The question I got stuck on is:

1. How fast does the block need to be going at the bottom of the ramp so that the acceleration of the block at the top of the loop is 4g?

- I thought this was simply A=v^2/r, where A=4g, giving me v=(4gr)^(1/2).

- I put in R=10, my answer is wrong, and I guess it wasn't as simple I thought. :| How should I actually go about this?

I also don't get this question:

2. What is the speed of the block as it exits the loop if the normal force at the top of the loop was 80N.

-I made Fnet=normal force + mg, then substituted to get Fnet=80+(1kg)(9.8N)=898N.

- Made Fnet=(mv^2)/r, where r=10. Again, my answer is wrong, so am I just oversimplifying these problems? Is there a better way to do them?

Thanks so much in advance!

Lori-Anne

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