Physics - October 2007

2007-10-21 14:27:48 · 1 answers · asked by medsimas 2

whats the specific heat capacity of aluminium, iron, and copper
anf water too,,

2007-10-21 14:23:51 · 2 answers · asked by gunkedar 2

A parachutist of mass 68.7 kg jumps out of an airplane at a height of 1080 m and lands on the ground with a speed of 5.9 m/s. The acceleration of gravity is 9.8 m/s^2. How much energy was lost to air friction during this jump? Answer in units of kJ.

Please show work/explanation of how you reached answer. Thank you.

2007-10-21 14:18:14 · 2 answers · asked by splashhhh 1

An archer pulls her bow string back .324 m by exerting a force that increases uniformly from zero to 225 n. What is the equivalent spring constant of the bow? Answer in units of n/m.

b.) How much work is done in pulling the bow? Answer in units of J.

Please show work/explanation of how u arrived at your answer.

2007-10-21 14:14:22 · 1 answers · asked by splashhhh 1

I realize that a double A has 1.5 Volts, but taking everything (including mAH of each) into consideration, I would like to know which would shine brightest and which would last longest.

2007-10-21 14:09:26 · 5 answers · asked by peachcobbler 3

At 20.0°C, a mainly silicon resistor has a resistance of 585 Ω, and a tungsten resistor has a resistance of 752 Ω. At this temperature, the silicon resistor has a temperature coefficient of resistivity of −0.070°C−1 and the tungsten resistor has a coefficient of 0.0050°C−1.

2007-10-21 14:06:37 · 1 answers · asked by Rachel H 1

are displacement and force in hooke's law always opposite in signs?

2007-10-21 14:01:17 · 3 answers · asked by sathi 2

In physics we did a lab and shot rockets at different angles. I can't figure out these answers.

My only known information is the fifteen degree theta angle at which we shot it, and that the time was 1.77 seconds before it hit the ground. (also, it is known that when going up there is no acceleration, and going down the acceleration is -9.81 m/s/s)

I need:

1] intial vertical velocity at the time of launch, in m/s
2] max height reached in meters and feet
3] resultant velocity at which the rocket was launch in m/s and mi/h
4] horizontal velocity in m/s
and 5] horizontal range in meters and feet.

We have to use the kinematic equations, trig functions, and the pythag. theorem.

help?

2007-10-21 13:59:16 · 1 answers · asked by CL 1

Ff=4.0n on a 5.0kg blocky
ff=8.0n on a 10kg blockx
fa=30n south on blockx
calculate the action and reaction forces.

2007-10-21 13:41:00 · 1 answers · asked by Anonymous

2007-10-21 13:39:10 · 3 answers · asked by Anonymous

It would require a lot of force to open a safe underwater, like they did in the Italian Job.

I am looking for an equation that would figure out how much force you will need to open an airtight container [such as a safe] underwater, also, under different depths.

Thanks

2007-10-21 13:21:25 · 2 answers · asked by G S 1

Okay, in my physics class we are working on launching projectiles at an angle. I'm doing a lab that involves launching an object at different angles, but maintaing the same launch spped. I've discovered that the angle that gives the greatest range is 45 degrees, but I don't understand why it is that way.

Also, changing the launch speed but not the angle produces a graph that slants upward. So the mathmatical relationship should be linear, correct??

2007-10-21 13:17:53 · 3 answers · asked by Anonymous

A roller coaster car of mass 1500 kg starts a distance H = 23 m above the bottom of a loop 15 m in diameter. Friction is negligible.

a) Find the speed of the coaster when it is upside down at the top of the loop.

b) Find the downward force of the rails on the car when it is upside down at the top of the loop.

2007-10-21 13:16:46 · 1 answers · asked by Anonymous

There was a gal who had had a couple of accidents, so her grandma gives her a large sum of money to buy a brand new Volvo. The only condition is that when she gets the car, grandma wants to see it to make sure she didn't buy that Firebird. She drives to grandma's house which is 120 miles away. Assume that she lives right on the highway, and so does grandma -- there's no time lost accelerating(you know)
Because she's not eager to get there, she sets the cruise control for 40 mph and drives the 120 miles to grandma's house. She doesn't want to spend too much time with grandma; so she shows grandma the car and leaves. On the way back she sets the cruise control for 60 mph. same road, same 120 miles, and when she gets home she thinks,"I drove 120 miles up with 40 mph and 120 miles down with 60 mph thats 240 miles, my average speed was 50 mph, so it should have taken me 4.8 hours,right? That's 240 divided by 50 (average speed) comes out to 4.8. But it took 5 hours. How can that be??

2007-10-21 13:14:33 · 5 answers · asked by tuazeee 2

Vector V1 is 7.44 units long and points along the -x axis. Vector V2 is 4.39 units long and points at +55.0° to the +x axis.
I've figured:
V1x= -7.44
V1y= 0
V2x= 2.518
V2y= 3.596

magnitude= 6.0957

but i can't figure what the direction = ?° (counterclockwise from the +x axis is positive)

2007-10-21 13:12:49 · 1 answers · asked by hahahahahaha 1

The exact question which I'm having trouble with:

What is the acceleration due to gravity at a distance of 2 Earth radii above Earth's surface?

I have, no idea what this thing is asking. Isn't a radius a distance between the center of an object and its outer shell? So is this thing asking me the pull of gravity on an object, by earth, if the object is twice the distance from earth's surface than the surface and the core? What is the equation for that?

2007-10-21 13:11:48 · 2 answers · asked by paladin_hammer 1

2007-10-21 12:49:45 · 4 answers · asked by Anonymous

If density= mass/volume
than what would the formula be to find mass?
-------------------------------------------------------------
would volume= mass/ density
or volume= mass X density?

2007-10-21 12:15:20 · 6 answers · asked by Anonymous

title says it. i have a pedestal fan, that for the last few days has been making squeaky noises. now when i turn it on, it makes half a spin and then stops short. i can still hear the engine making an effort. when its not on i can make it spin smoothly. but when its on i cant make it spin easily since it stops at certain zones. i've cleaned it internally. and oiled it at the bearings.

2007-10-21 12:10:54 · 1 answers · asked by oldarney 3

please help me solve this problem. i need the formula and what is given. i also need a step by step help to solve it. Please help me with anything you can. thanks :)

A man is pulling on his dog with a force of 70.0 N directed at an angle of +30.0 degrees to the horizontal. Find the x and y componets of this force.

2007-10-21 10:54:14 · 1 answers · asked by Anonymous

2007-10-21 09:57:46 · 1 answers · asked by cutie 2

in less then 100 words perfurably?

2007-10-21 09:21:25 · 4 answers · asked by Anonymous

What is the magnitude of the momentum of a 19 g sparrow flying with a speed of 9.1 m/s?

the units are kg·m/s

2007-10-21 08:54:14 · 2 answers · asked by maxk222 1

A parallel plate capacitor in a vacuum has a capacitance of 6.4 nF. The capacitor is fully charged by connecting it across a 128V voltage source. The voltage is then removed without discharging the capacitor, and the space between the plates is filled withe a dielectric material. the capacitance is measure again and found to be 28.8 nF

So i found that voltage across the plates is 28.44V after inserting the dielectric. And that the charge on the plates will remain the same 8.192*10^-7 C.

Suppose the dielectric was inserted before removing the voltage source. Will the charge on the plates increase, decrease or remain the same? and what is the voltage across the plates now?

2007-10-21 08:41:17 · 2 answers · asked by I S 1

2007-10-21 08:35:00 · 2 answers · asked by simochka 1

What is your opinion on this? It blew my head off. Have always been into quantum physics but wow! If everyone was to see this, what effect would it have on the planet?

2007-10-21 07:28:02 · 5 answers · asked by ? 5

a 20g pellet is fired into a 200g wooden block initially at rest on a horizontal surface.
the block slides 5.1m before stopping.
the friction coefficient μ is 0.7 between block and surface.
what was the pellet's speed just before impact?

im having trouble with this because the only momentum questions i have ever done are the ones where at least one velocity is given, so i'm struggling here.

my thoughts on it are its something to do with kinetic energy, energy lost due to friction etc, and i worked out the pellet's speed on impact is 11x that of the pellet-block combination when it moves off after impact.

i dont care about the final answer really, just the method of finding it.
cheers.

2007-10-21 07:16:51 · 3 answers · asked by fpa06mr 5

A 2kg object is moving across a table at a speed of 2.0 m/s againt a force of friction of 6.0 n. The applied force is suddenly increased by 1.0n. How fast will oject be moving after 3.0s

2007-10-21 06:27:09 · 2 answers · asked by Anonymous

To pull a 50kg crate across a frictionless floor a worker applies a force of 210N, directed at 20 degrees above the horizontal. As the crate moves 3m, what work is done on the crate by...
(a) the workers force
(b) the weight of the crate
(c) the normal force exerted by the floor on the crate
(d) total work done on the crate

i have letter (d) is it w=(210N)(3) (cos20) right? or is that for (a)?
also, is the nornal force 9.81*50kg

2007-10-21 06:15:18 · 2 answers · asked by silyrabbittwixR4kidz 3

A distance of 43 ft from the pad, a man observes a helicopter taking off from a heliport. If the helicopter lifts off vertically and is rising at a speed of 40 ft/sec when it is at an altitude of 125 ft, how fast is the distance between the helicopter and the man changing at that instant?

2007-10-21 05:43:07 · 2 answers · asked by samantha 5