# Search results

1. ### Kinetic and Potential Energy?

Kinetic and Potential Energy!?! This problem is totally confusing me..can someone please explain it...:confused: A 3.0 kg object subject to a restoring force F is undergoing simple harmonic motion with a small amplitude. The potential energy U of the object as a function of distance x from...
2. ### Work/Spring problem

The exact problem is: A massless spring is between a 1-kilogram mass and a 3-kilogram mass, but it is not attached to either mass. Both masses are on a horizontal frictionless table. In an experiment, the 1-kilogram mass is held in place, and the spring is compressed by pushing on the...
3. ### Work problem

Ok...Here is the problem. A block of mass 4 kilograms, which has an initial speed of 6 meters per second at time t=0, slides on a horizontal surface. (a) Calculate the work W that must be done on the block to bring it to rest. For this problem, I used the formula W= 1/2mvf ^2– 1/2mvi ^2...
4. ### Velocity and Acceleration

Ok, I have this problem... The first 10 meters of a 100 meter dash are covered in 2 seconds by a sprinter who starts from rest and acceleraties with a constant acceleration. The remaining 90 meters are run with the same velocity the stprinter had after 2 seconds. a) Determin the sprinter's...
5. ### Moment of inertia

does anyone know an easier way to determine which formula is used for calculating moment of inertia? i have all the formulas and descriptions, but i have trouble figuring out which formula to use based on what is given in the problem. any ideas thatll help me?
6. ### Pool ball collision physics

I swear, this is the last problem that I have. Here it goes... A pool ball having a mass of .65 kg experiences an elastic collision with a croquet ball having a mass of 1.38 kg. The pool ball had been rolling for 4.3 seconds, having covered a distance of 22.6 meters during that time. The...
7. ### Confused on velocity

Here's my predicament... A 30.0 kg shopping cart full of groceries sitting at the top of a 2.0 meter hill rolls until it hits a tree stump at the bottom of the hill. Upon impact, a .25 kg can of peaches flies out of the cart. What is the velocity of the can as it leaves the cart? I tried...
8. ### Solving for time and displacement

Ok, here's the problem that I am working on now. Sarah is walking at a speed of 1.5m/s when she accidentally slips on a patch of ice whose coefficient of kinetic friction is 0.060. If Sarah has a mass of 40.0 kg, how long before she comes to a stop on the ice? I'm stuck because I don't know...
9. ### Helicopter final velocity help

Okay...I am think that I am totally lost on this problem. A helicopter holding a 70-kilogram package suspended from a rope 5.0 meters long accelerates upward at a rate of 5.2 m/s^s. When the upward velocity of the helicopter is 30 meters per second, the rope is cut and the helicopter...
10. ### Mouse trap cars

Does anyone have any tips on how to make/build a mouse trap car, with the mouse trap being the only source of energy? I have an idea of what it should look like, and how it should work, but I'm really not sure. Is there any helpful hints that I might need while building my project for my physics...
11. ### Collisions of hockey pucks

Okay, here's the problem I'm working on... A .50 kg hockey puck moving at a speed of 5.70 m/s collides with a stationary hockey puck of equal mass. After the collisions, the first puck moves off in a direction 60 degrees to the left of its original direction, while the second puck moves off at...
12. ### Naming Ionic formulas

Okay, I am so confused about how to determine whether or not you have to use the parenthesis with the Roman numeral. It is confusing me because some of the compounds that I have to write the name for, are ternary compounds, and I'm not sure which order they go in. :confused:
13. ### Find the magnitude of the force that stops the bullet

HELP Please!! Ok, I am totally lost on how to solve this problem: A 5 g bullet moving at 600 m/s penetrates a tree trunk to a depth of 4 cm. a. use work and energy considerations to find the magnitude of the force that stops the bullet b. assuming that the frictional force is constant...
14. ### Find the coefficient of kinetic friction problem

Ok, here is my dilemma: A flight attendant pulls her 70.0 N flight bag a distance of 253 m along a level airport floor at a constant velocity. The force she exerts is 40.0 N at an angle of 52 degrees above the horizontal. Find the following: a) the work she does on the flight bag b) the work...
15. ### More energy is needed to walk down stairs than to walk horizontally

Ok, here is my problem: Explain why more energy is needed to walk down stairs than to walk horizontally at the same speed? I don't get it, its against logic isn't it. Is it because of the height, that causes the energy walking down the stairs to be greater? That's the only explanation that I...
16. ### Negative or not?

:confused: I know that you can have a negative acceleration, which would be considered deceleration, but is it possible to have a negative speed? It may sound like a stupid question to some people, but I am completely baffled.
17. ### How fast was the ball moving when it left the pool table?

HELP!!! PlEaSe Okay, here is my problem: In a wild shot, Bo knocks a pool ball of mass of .85 kilograms offa 95-cm high pool table, and the ball hits the floor with a speed of 6.0 m/s. How fast was the ball moving when it left the pool table? I don't want to know the answer, I just want to...
18. ### Coefficient of Kinetic friction

Ok, in this problem, I am given theta, which in 30 degrees, and acceleration, which is 1.2 m/s^2. How do I solve for the coefficient of Kinetic friction without the mass? :confused: