Physics - December 2007

A 40.0 cm diameter wheel accelerates uniformly from 205 rpm to 395 rpm in 6.0 s. How far will a point on the edge of the wheel have traveled in this time?
in meters

2007-12-18 10:12:56 · 2 answers · asked by joe s 1

(A)Two students on roller skates stand face to face then push each other away. One student has a mass of 96kg and the other student has 60kg.

Find the ratio of the magnitude of the first student's velocity to the magnitude of the second student's velocity.

(B) A 2080 kg car moving east at 10.1 m/s collides with a 3270 kg car moving 3.99m/s east. The cars stick together and move east as a unit after the collision at a velocity of 6.27 m/s.

What is the decrease in kinetic energy during the collision in units of m/s?

2007-12-18 09:59:35 · 3 answers · asked by Catalina 2

2007-12-18 09:27:53 · 6 answers · asked by Alexander 6

You visit a planet that turns on its axis once every 24 hours. The radius of the planet at its equator is 5.72×106 meters.
You would feel weightless at the equator on this planet, if it rotated fast enough so that the centripetal acceleration at the planet's surface was equal to the acceleration due to gravity (which in this case is 12.5 m/s2). Calculate the new rotational period for this planet necessary to produce this effect! Calculate the period in hours.



(I tried using the equation a=((2*pi*r*f)^2)/r but I get the wrong answer every time.)

2007-12-18 09:25:39 · 3 answers · asked by ellenangel364 3

A 0.10 kg piece of copper at an initial temperature of 95°C is dropped into 0.20 kg of water contained in a 0.28 kg aluminum calorimeter. The water and calorimeter are initially at 15°C.
What is the final temperature of the system when it reaches equilibrium?


Thanks everyone!

2007-12-18 09:20:07 · 1 answers · asked by Anonymous

1.) When a spring is released, the rod pushes against one cart with a given force. This cart pushes back with an equal force. Explain why this means that the total force on the system of the two carts is zero.


2.) If two carts have the same mass, how would you expect their velocities to compare with each other ? Why?

2007-12-18 09:17:11 · 1 answers · asked by Danielle P 1

Would there remain molicules of water between the the wet surface and the persons sole.

2007-12-18 09:01:17 · 3 answers · asked by Riccard P 1

I do.

lol!

2007-12-18 08:58:52 · 8 answers · asked by Anonymous

1.) A heavy-duty stapling gun uses a 0.173 kg metal rod that rams against the staple to eject it. The rod is pushed by a stiff spring called a "ram spring" (k = 37479 N/m). The mass of this spring may be ignored. Squeezing the handle of the gun first compresses the ram spring by 3.90*10^-2 m from its unstrained length and then releases it. Assuming that the ram spring is oriented vertically and is still compressed by 6.20*10^-3 m when the downward-moving ram hits the staple, find the speed of the ram at the instant of contact.

2.) A 1.0 kg object is suspended from a vertical spring whose spring constant is 105 N/m. The object is pulled straight down by an additional distance of 0.25 m and released from rest. Find the speed with which the object passes through its original position on the way up.

Not sure how to do these; help would be appreciated.

2007-12-18 08:48:45 · 1 answers · asked by Anonymous

When a water gun is fired while being held horizontally at a height of 1.23m above ground level, the water travels a horicontal distance of 1.28m.

The acceleration of gravity is 9.81 m/s2.

A. Find the initial velocity of the water.

A child, who is holding the same gun in a horizontal position, is sliding down a 41º incline at a constant speed of 1.34 m/s. The child fires the gun when it is 1.4 m above the ground and the water takes .451 s to reach the ground.

b. How far will the water travel horizontally?

2007-12-18 08:44:21 · 2 answers · asked by softball_linz_06 1

This is what I have: the air above wings travels farther and faster than the air below, the air below wings is denser and pressure is greater, air below wings creates lift

Can someone explain this to me more clearly? I'm reading this and I sort of get it, but I still don't understand why/how..

2007-12-18 08:37:08 · 11 answers · asked by Jenny 3

A 27.0 kg block is connected to an empty 1.00 kg bucket by a cord running over a frictionless pulley (Fig. 4-57). The coefficient of static friction between the table and the block is 0.415 and the coefficient of kinetic friction between the table and the block is 0.320. Sand is gradually added to the bucket until the system just begins to move.

Here's the picture: http://i12.tinypic.com/6t3hki0.gif

Thanks soo much for your help!!

Please check out my other questions...even if you are not sure how to do this one. Thanks!!!!!!

2007-12-18 08:23:16 · 1 answers · asked by Bollywood Masti 4

Two identical masses are attached by a light string that passes over a small pulley. The table and the pulley are frictionless. Calculate the masses' acceleration and the tension on the string.

Please show/explain all work and show what formulas were used.

2007-12-18 08:16:41 · 1 answers · asked by Anonymous

2007-12-18 08:15:46 · 3 answers · asked by wasnt_invited 1

A force of 26.0 N is required to start a 3.2 kg box moving across a horizontal concrete floor. If the 26.0 N force continues, the box accelerates at 0.50 m/s2. What is the coefficient of kinetic friction?

I got answers like 2.8, .051, 1.6, and .625

None of these were correct. Please help and explain your answers.

Also, I have posted other such questions. Even if you don't know how to do this one, please check those out in case you know how to do those. Thanks!

2007-12-18 07:54:30 · 2 answers · asked by Bollywood Masti 4

we had a lab were we built a parachute and was given a lab sheet i have to draw the parachute and label all the forces that act on it... im guessing i need to label weight and the normal force but what other forces do i need to label??? friction?air resistance?

also on a kite, how is a kite similar and different to a parachute??? all i have so far is one stays in the air and one drops but i dont think that is acceptable to put down.

2007-12-18 07:49:46 · 2 answers · asked by molly 1

Up near Truckie, the Schmidt boys are inner tubing down a snow covered creek bed. Fred and his tube weigh 225 pounds together. The creek bed is a 20 degree incline. How fast will Fred be going at the end of a 30 meter run?

Please show/explain all work. Please show all formulas used.

2007-12-18 07:49:13 · 1 answers · asked by Anonymous

2007-12-18 07:27:19 · 13 answers · asked by Anonymous

You notice that the ping-pong ball sinks into the water as it falls.

Explain.

2007-12-18 07:21:49 · 8 answers · asked by Anonymous

2007-12-18 06:54:55 · 9 answers · asked by bigjoerodbigrod 1

Exmp: someting weighs 10 tons. something has a mass of 10 tons.

2007-12-18 06:39:23 · 18 answers · asked by Uchimataman 1

With our current reliance on fossile fuels and other forms of stored energy (coal, chemical) we are releasing excess waste heat (among other things) into the atmosphere. Looking for alternative 'green' energy sources is a great ideal, but my feel this could further impact the environment.

Assuming for argument that we can build a large mirror array in space and send captured solar energy safely to earth. That amounts to a new input of energy into our (closed?) system. How will we deal with the excess heat generated as a by product of doing work with that energy? Is there a way for us to efficiently radiate that heat into space?

2007-12-18 06:34:18 · 7 answers · asked by Web Wonder 1

what does this mean? please give me examples what is not constant?

2007-12-18 06:23:36 · 6 answers · asked by Narok 1

Your boss cuts you off when you try to explain the concept of buoyant force to him. Being the smart*** that you are, you come back later with a life vest full of lead pellets.

Explain.

2007-12-18 06:23:07 · 4 answers · asked by Anonymous

Hi,

I want to immerse a diode in various water baths but I'm not quite sure how I can do this as I can't insert a diode directly into a water bath. At the same time though, I want the diode to be able to respond to the change in temperature surrounding the diode.

I had a look at heat shrink tubing on the internet but that will "shrink" the heat. Also, another way (thanks to amansscientiae) is to place the diode directly in oil inside a test tube. Would it be ok for me to do this though? (As I will need to connect wires on both sides of the diode.)

2007-12-18 06:19:55 · 5 answers · asked by Anonymous

A person doing a chin-up weighs 700 N, disregarding the weight of the arms. During the first 24.0 cm of the lift, each arm exerts an upward force of 358 N on the torso. If the upward movement starts from rest, what is the person's speed at this point?
m/s

2007-12-18 06:05:19 · 4 answers · asked by Anonymous

If I have a 3V Battery and connect it to a bulb of resistance 12 ohm I should have a current of 0.25A flowing through.

So then if I connect two 3V Batteries in Parallel, should I still have 0.25A in the circuit?

I always thought that batteries in parallel doubled the current in the circuit but I have found it to be different. So what increases. Does the maximum load of the circuit increase? I mean does it mean that this setup could provide up to double the current than that of only one battery?

2007-12-18 06:04:57 · 7 answers · asked by alanjb 1

2007-12-18 06:03:03 · 10 answers · asked by Narok 1

wondering

2007-12-18 05:59:26 · 3 answers · asked by Anonymous

He is going 8 m/s on a straight plain when he comes to a hill. The hill is 6 meters tall. What is the velocity of the person and the bike when they reach the bottom of the hill. Don't take air resistance into consideration.

There isnt enough information to do the problem.
I dont understand how you are supposed to get the length of the hill (x) or the time it took to get down the hill.

Can someone help me?

2007-12-18 05:53:49 · 3 answers · asked by Derek S 1