# Re: Physics - drwls #2

Posted by winterWX on Monday, March 19, 2007 at 11:54pm.

A small block of mass m = 4.0 kg can slide along the frictionless loop-the-loop. The block is released from rest at point P, at height h = 23R above the bottom of the loop (R is the radius of the loop). Express your answers in the form ngR, where n is the number you will calculate.

a) What is the potential energy when the block is at point P? [at the very top of loop] (Assume the gravitational potential energy of the block Earth system is taken to be zero at the bottom of the loop).

b) What is the potential energy when the block is at point Q (halfway up the loop)?

c) What is the kinetic energy when the block is at the top of the loop?

* Physics - drwls? - drwls, Tuesday, March 20, 2007 at 2:19am

We don't do homework for you here. Show us some effort and someone will critique your work or thought process.

--------------------------

*note: i cant post the diagram.. but it looks like the number "6" slightly tilted 45 degrees counterclockwise

- potential energy for problem (a).. would be:

U = (4.0 kg)(9.8 m/s^2)(23R)
U = 901.6R

- problem (b) is similar:

U = (4.0 kg)(9.8 m/s^2)(2R)

- problem (c) would be:

K = 1/2mv^2
K = 1/2(4.0 kg)(???^2)
.. but what would i use if a velocity is not given?

----- and i'm also having difficulty understanding on how to express my answer in the form "ngR" .. what does that mean? .. is n just a random variable?

change in PE = - (change in KE). "V" is what you solve for.

I have no idea what they mean by "nGR"

On b, PE= mgh. If the block is halfway up the loop, wouldn't that height be R, not 2R>
On c,
Wouldn't the KE be equal to the change of PE, which would be the same as the original PE in the a)?

Your answer will be in the form of Number*gR . n the number is most certainly not random. It is what you calculate.

Winter:
A couple of notes for you. Please don't indentify tutors in the subject line. Most of us don't like our names in headlines. Don't do that.
Secondly, in reading your work, I think you would greatly benefit from a tutor once or twice a week. Discuss this with your parents. Another student I think could help you a lot. You don't seem to me to have a lot of confidence in your ability to think out these problems, and that is the crux of your difficulty. My experience tells me that a tutor would help greatly. My experience also tells me that it would be unwise to delay this decision.

1. 👍 0
2. 👎 0
3. 👁 129
1. mhwpcvub dcxzps chrvm qtxd ujhdlkpfg cvetsni nlscwp

1. 👍 0
2. 👎 0

## Similar Questions

1. ### chemistry

Posted by Bret on Friday, March 16, 2007 at 10:44am. what is the oxidation number for nitrogen in the following? NH3 NO2 1- N2 NO2Cl N2H4 For Further Reading chemistry - bobpursley, Friday, March 16, 2007 at 11:26am We will be

asked by Bret on March 16, 2007
2. ### RE: phhysics

Posted by Charlene on Friday, March 23, 2007 at 3:00am. picture in your mind a block that slides without friction down a ramp that is inclined at an angle (q) above the horizontal. Initially the block is at rest a distance (s) in

asked by Charlene on March 23, 2007
3. ### Physics - drwls

Posted by winterWX on Monday, March 19, 2007 at 11:51pm. A 2600 kg truck traveling north at 38 km/hr turns east and accelerates to 55 km/hr. What is the change in the truck's kinetic energy? What is the magnitude of the change in

asked by winterWX on March 22, 2007
4. ### Repost repost physics

Posted by Meredith Mcneeds Help! on Monday, November 19, 2007 at 8:08pm. Hey, ok so I am supposed to be helping my cousin this with this physics problem, and this is the only one that has ever stumped me! Neutral metal spheres A

asked by Meredith Mcneeds Help! on November 19, 2007
5. ### PHYSICS - still cant get it

A 0.30-kg softball has a velocity of 12 m/s at an angle of 30° below the horizontal just before making contact with the bat. What is the magnitude of the change in momentum of the ball while it is in contact with the bat if the

asked by winterWX on February 24, 2007
6. ### science

Posted by Josh on Saturday, March 17, 2007 at 10:58pm. How many grams of hydrochloric acid are required to react completely with 4.30g of zinc? How many molecules of gas will be produced? For Further Reading science - DrBob222,

asked by Josh on March 18, 2007
7. ### Physics

Two blocks are connected by a cord passing over a small frictionless pulley. The angle is 30 degrees, and the mass of the small block is m=15kg. If the coefficient of friction between the small block and the inclined plane is .25

asked by T.J. on May 9, 2014
8. ### Algebra 2

Posted by Christian on Monday, May 7, 2007 at 11:34am. The area of a rectangular blanket in square centimeters is 40x^2+2x-65. The width is 4x-5 cm^2. Find the dimensions of the blanket in terms of x. For Further Reading Algebra 2

asked by Christian on May 7, 2007
9. ### physics - drwls?

The flywheel of a steam engine runs with a constant angular speed of 250 rev/min. When steam is shut off, the friction of the bearings stops the wheel in 2.1 h. At the instant the flywheel is turning at 75 rev/min, what is the

asked by winterWX on March 13, 2007