Physics - March 2007

Three 60.0 W, 125 V lightbulbs are connected across a V = 125 V power source, as shown in Figure P18.48. (Assume that the resistance of each bulb is constant even though, in reality, the resistance increases markedly with current.)

Figure P18.48
http://www.webassign.net/sercp/p18-48alt.gif

(a) Find the total power delivered to the three bulbs.
W
(b) Find the potential difference across each light bulb. VR1 = V
VR2 = V
VR3 = V

2007-03-01 12:50:32 · 1 answers · asked by Anonymous

2007-03-01 12:50:21 · 1 answers · asked by michelle g 2

i know how electricity is made but what is electricity itself made of?

2007-03-01 12:27:16 · 12 answers · asked by Death follows us all 5

i need to know the thing/s that make electricity in saltwater.....thanx 4 the help!

2007-03-01 12:20:26 · 5 answers · asked by Essa 2

a certain nut is known to require forces of 40N exerted on its shell from both sides to crack. what force components, perpendicular to the handles, will be required when the nut is placed in the nutcracker? the handle is 12 cm long and the nut is 2.6 cm from the end

2007-03-01 11:42:20 · 1 answers · asked by abchawaiixyz 1

I did my Physics HW and it’s worth a test grade so can someone check and make sure that I did them correctly?
PLEASE, I WILL APPRECIATE ALL THE HELP THAT I CAN GET –IT’S NOT REALLY THAT LONG. I NEED THESE ANSWERS TO BE RIGHT AND I HOPE YOU GET THE EQUATIONS, IT’S HARD TO TYPE PHYSICS PROBLEMS ON HERE …. GOD BLESS!


#1) A child on a merry-go-round is moving with a speed of 1.35 m/s when 1.20m from the center of the merry-go-round. Calculate (a) the centripetal acceleration of the child, and (b) the net horizontal force exerted on the child (Mass=25kg)

For (a) I did Centripetal Acc= V^2/ (r) and got 1.5 m/s^2
And for (b) I got Fnet=mv^2(r) and I got 38N

#2) A girl sits in a tire that is attached to an overhanging tree limb by a rope 2.10m in length. The girl’s father pushes her with a tangential speed of 2.50 m/s. If the magnitude of the force that maintains her circular motion is 88N, what is the girl’s mass?

I did Fc=m v^2/(r) then m=Fc r/(v)^2 (I got this equation from our packet) and my answer came out to be 29.5kg.

#3) A bicyclist is riding at a tangential speed of 13.2m/s around a circular track w/ a radius of 40m. If the magnitude of the force that maintains the bike’s circular motion is 377N, what is the combined mass of the bicycle and rider?

I did m= Fc (times) r/(v)^2 (sorry, I can’t type out the exact formula) and I got that the mass is 86.5kg but I don’t get what it means by COMBINED MASS DO I HAVE TO ADD SOMETHING TO THAT? HELP?

#4) A 20.0kg child wishes to balance on a seesaw with a child of 32kg. If the smaller child sits 3.2m from the pivot, where must the larger child sit?

I did (m1)(g)(d1) = (m2)(g)(d2) and so
(20)(9.8)(3.2) =(32)(9.8)(d2) and I got d2=2m …. I hope this makes sense, most importantly, I HOPE IT’S RIGHT!

#5) Tarzan plans to cross a gorge by swinging in an arc from a hanging vine. If his arms are capable of exerting a farce of 1400N on the rope, what is the maximum speed he can tolerate at the lowest point of his swing? His mass is 80kg and the vine is 4.8m long.

I used the same equation …. Since Fc=mv^2/(r) then v^2= Fc r/m and then I got v^2 =9.16 m/s ….
#6)Tarzan tries to cross a river by swinging from one bank to the other on a vine that is 10m long. His speed at the bottom of the swing, just as he clears the surface of the river, is 8m/s. Tarzan does not know that the vine has a breaking strength for 1.0x10^3 N. What is the largest mass Tarzan can have and make it safely across the river?

I did m=Fc r/vt^2 (as in Tang. Velocity) … and I got m=156.25kg. Is it right?

2007-03-01 11:27:47 · 2 answers · asked by BeatyIsInTheEyesOfTheBeholder 1

2007-03-01 11:06:29 · 9 answers · asked by cutie pie 1

The bar is at a 30 degree angle to the horizontal. Not taking into account air resistance what is the angular velocity of the bar after its center has dropped 10 feet.

2007-03-01 10:52:14 · 3 answers · asked by brcalaska 1

Physics Submarine Question?
A submarine of mass 2.1 *10^6 kg and initially at rest fires a torpedo of mass 260 kg. The torpedo has an initial speed of 100.9 m/s. What is the initial recoil speed of the submarine? Neglect the drag force of the water.

2007-03-01 10:47:21 · 2 answers · asked by Anonymous

A block of mass 1.37 kg is kept at rest as it compresses a horizontal massless spring (k = 84.7 N/m) by 6.27 cm. As the block is released, it travels 0.502 m on a rough horizontal surface before stopping.

The acceleration of gravity is 9.8 m/s^2 :

Calculate the coefficient of kinetic friction between surface and block.

2007-03-01 10:27:01 · 1 answers · asked by mansun15 1

I've heard about Cerenkov radiation. Says When high velocity particles travel faster than the speed of light in a medium...I thought light was a wave(I understand light has properties of a wave and a particle so its convenient to think in terms of one or the other..but what is this particle they are speaking of? I assume they mean a Photon? So then, "when light travels faster than c" is that what they mean? And why dont they just say something to that effect then? Oh and light can be electromagnetically charged?

2007-03-01 10:25:35 · 2 answers · asked by optik_0v3rd0se 2

2007-03-01 10:11:39 · 6 answers · asked by PONCHO 1

the length of a string is 45 cm, if the period of the wave on the string is 1.2 x 10^-3 s. deduce that the speed of the wave is 250 m/s^2

2007-03-01 10:10:06 · 3 answers · asked by avemaria 2

Say...
You're underwater in an giant aquarium...
And it falls 30 feet...
And hits the ground...

Would the water cushion you in any way?

2007-03-01 10:08:42 · 10 answers · asked by Gottlos 4

2007-03-01 10:02:15 · 4 answers · asked by Anonymous

2007-03-01 09:52:47 · 11 answers · asked by Eli 2

An 800kg space station is circling Earth in a circular orbit with a radius of 10,000km. Its orbit is to be changed to a larger circle with a radius of 27,000. How much energy is required to accomplish this. The mass of Earth is 5.97 * 10 ^24, G=6.67 * 10^-11.
How do I solve this?

2007-03-01 09:42:43 · 3 answers · asked by veghead566 1

A 302 kg block is released at height h = 4.4 m as shown. The track is frictionless except for a portion of length 6.6 m. The block travels down the track, hits a spring of force constant k = 1993 N/m, and compresses it 2.6 m from its equilibrium position before coming to rest momentarily.

The acceleration of gravity is 9.8 m/s^2.

Determine the coefficient of kinetic friction between surface and block over the 6.6 m track length.

2007-03-01 09:41:18 · 2 answers · asked by lennox lewis 1

I don't have any idea how to solve this, and this is for my test tomorrow.. please.. give me some ideas or anything you can offer..
Here's the problem:

So there's a block that is hanging by two cords on each end of the block....
the lengths of the cords are described by the letter "l"...
The block's mass is "M"...

so here's the scenerio.. the block hangs.. then, there's this bullet with a mass (m) that hits the block with such speed (v).. and gets implanted into the block.. the impact of the bullet.. made the block go up by a certain height (h)...

the problem is something like that...
find the height after it impacts...
then find the speed of the bullet...
then find the tension of the cord...

there are no numbers.. just letters.. solve this problem any which way you want...

good luck!! please help me!!
if you need more information... that I forgot to imput.. please.. let me know.. thanks!!

2007-03-01 09:30:00 · 6 answers · asked by Anonymous

Why is the apparent weight of a person on the top and bottom of the loop of a rollar coaster different?
I know it has something to do with centripetal force (and gravity)...thanks!

2007-03-01 09:09:27 · 3 answers · asked by sandcastlesinair 1

A 5.9 kg mass is attached to a light cord that passes over a massless, frictionless pulley. The other end of the cord is attached to a 3 kg mass.

The acceleration of gravity is 9.8 m/s^2.

Use conservation of energy to determine the final speed of the first mass after it has fallen (starting from rest) 5.3 m: Answer in units of m/s.

2007-03-01 09:04:59 · 2 answers · asked by henryissac 1

A.From one end of the conductor to the other end
B.with a speed of 300,000,000 m/s
C.back and forth between the ends of the conductor
D.through a relatively short distance

2007-03-01 08:55:50 · 3 answers · asked by Whiskers 3

2007-03-01 08:46:45 · 3 answers · asked by lemjoy 1

The Eternal Return is basically the theory that there is infinite time and a finite number of events, and eventually the events will recur again and again infinitely. Consider the world as a super-complex chess game. If games of chess are played one after another forever, eventually a game will be repeated since there is only a finite number of possible games, it is the same with the world; eventually events will recur in the same order. The world is an eternal process of coming to be and passing away. The process, however, has no beginning or end. Eventually every combination of matter and energy will be realized and repeated and infinite number of times


the reason it is disturbing is because you would live this life over and over and over again.

2007-03-01 08:42:44 · 8 answers · asked by Anonymous

The distance between two successive maxima of a transverse wave is 1.40 m. Eight crests, or maxima, pass a given point along the direction of travel every 7.0 s. Calculate the wave speed in m/s.

2007-03-01 08:19:24 · 1 answers · asked by Tennis2127 2

2007-03-01 08:19:20 · 2 answers · asked by crazystudent11 1

2007-03-01 08:14:25 · 1 answers · asked by victoria r 1

A cart loaded with bricks has a total mass of 12.3 kg and is pulled at constant speed by a rope. The rope is inclined at 24.5 degrees above the horizontal and the cart moves 12.5 m on a horizontal surface. The coefficient of kinetic friction between ground and
cart is 0.503.

The acceleration of gravity is 9.8 m/ s^2 :

How much work is done on the cart by the rope? Answer in units of J.

2007-03-01 08:09:34 · 1 answers · asked by mansun15 1

incorporating these components:

Pump, Cooling fins, Evaporation stage, Condensation stage, Liquid coolant.

2007-03-01 08:07:12 · 1 answers · asked by Anonymous

What common (or not) daily things or ocurrences apply the idea of Hooke's Law? [Give me a lot please....]

[Thank you very much!]

2007-03-01 08:03:12 · 3 answers · asked by inthemaking 2