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1. ### Work-Energy with friction

A rope and pulley have negligible mass, and the pulley is frictionless. The coefficient of kinetic friction between the first block (8 kg) and the table is \mu=.250. The blocks are released from rest. USE THE ENERGY METHODS TO CALCULATE THE SPEED OF BLOCK 2 (6 kg) after it has descended 1.5...
2. ### Hammer + Nail forces Will answer in response

1. A hammer is pounding a nail straight down into a wooden board. Just before the hammer hits the nail, the speed of the hammer is 1.2 m/s. The hammer drives the nail into the wood and stops after the nail goes in a distance of 0.95 cm. The weight of the hammer head is 6N, and in addition to...
3. ### Desperate situation.

i think you do have a chance, merely because you mentioned the main part: you enjoy learning this stuff. i hate to sound cliche, but it sounds as though the real problem is the drugs. I had a similar problem throughout the entire year as well, but i began to look at is as a reward for completing...
4. ### 2008 AP Physics C

What did people think? It may have been the hardest thing I've ever seen, and I am a very prolific calc and phys student. The E&M free response was very very ridiculous, especially #2 where you had to plug in different devices at the terminal and find the current in the parallel resistor. I...
5. ### Want to know correct answer for electric field + potential question

can't you just replace (\cos\tan^{-1}\frac{a}{x}) with \frac{x}{\sqrt{(x^2+a^2)}} ...or is that what shootingstar was saying
6. ### Just some conceptual stuff about car crashes

i figured it out: its because during the collision between the car+truck, its inelastic so momentum is conserved and thus forces is conserved as well (impulse = Ft); however, the two dummies never actually collide with each other and thus do not conserve momentum. Instead the dummies collide...
7. ### Just some conceptual stuff about car crashes

Homework Statement During a crash test, dummy x12 has a mass of 80 kg and rides in a 1120-kg car. Dummy y17 has a mass of 80 kg and rides in a 7120-kg truck. The vehicles approach each other with velocities of 30 m/s (about 67 miles per hour) in opposite directions (car heading east). The...
8. ### Springs and friction and energy, etc.

mistake on title yea sorry about the title, it wouldn't let me edit it though. :tongue2: thanks for the help!
9. ### Springs and friction and energy, etc.

Homework Statement A small block of mass m is pressed up against a spring. The spring has constant k and is compressed a distance x. The block slides along a track up and around a loop of radius r and down and out on the far side, as shown. At the top of the loop, the loop exerts a...
10. ### U-substitution for finding v(t)

alright so i assumed that was correct and went on with the problem, but ran into trouble at c. ΣF = ma = mg - .05v a = mg/m - .05v/.25 a = g - .2v dv/dt = a dv/dt = g - .2v dv/(g - .2v) = dt ∫ dv/(g - .2v) = ∫dt ln(g - .2v)/.2 = t - c ln(g - .2v) = .2(t - c) e^{.2(t - c)}...
11. ### Is 1K equal to 1C

thats the measure for 0 Celsius in Kelvin
12. ### Is 1K equal to 1C

well 1 degree Celsius is equal to 274 Kelvin. the values of each degree are the same though, so I'm not sure what he means by prove it. perhaps you could list the temperature of absolute zero in kelvin and Celsius, then do the same for the freezing and boiling points of water...
13. ### U-substitution for finding v(t)

so just to make sure I am correct, \int\frac{dv}{g-.2v} is \frac{ln(g-.2v)}{.2} + constant
14. ### Two Parallel Wires( in 2 hrs)

perhaps his answer is wrong by mistake? talk to other people in the class
15. ### U-substitution for finding v(t)

Homework Statement A .25kg ball is dropped from rest. Air resistance is f= -.05v a. find v(t) b. What is the terminal velocity of the ball? c. At what time does the ball reach 50% of its terminal velocity? 90%? Homework Equations F=ma F= mg - .05v The Attempt at a Solution Began to...
16. ### Top Undergrad Engineering (specifically mechanical, electrical, and chemical)

The top programs AFTER: MIT UC-Berkley Stanford i goofed off my freshman and sophmore years of HS, but have picked it up now, so I'm looking for engineering. I know Vanderbilt stacks up in the top 10, but I'm not sure which other programs are good. If you can, post some of your...
17. ### Photoelectric effect

the mathematics are correct, I'm just not sure if I'm using the correct forumlas
18. ### Photoelectric effect

1. Light of a wavelength 410nm is incident on a metal target and an electron is eject from the surface. The work required to remove this electron from the metal is 3.0 x 10^-19 J. The elctron then travels straight to a collection plate. The different in electric potential between the collector...