# Search results

1. ### Pendulum beam Problem

Homework Statement On the construction site for a new skyscraper, a uniform beam of steel is suspended from one end. If the beam swings back and forth with a period of 1.10 s, what is its length? Homework Equations T=2*pi*sqroor (L/g) The Attempt at a Solution...
2. ### Revolutions of an electron

Homework Statement A hydrogen atom exists in an excited state for typically 5.79 ns. How many revolution would an electron make in the n=2 state before decaying? Homework Equations L=m*v*Rn=h(bar)*n w=v/Rn Rn=n^2*Ao Ao=.053 nm The Attempt at a Solution Rn=4*.053=.212 nm...
3. ### A protons Min KE

Homework Statement A proton is confined in a uranium nucleus of radius 7.41 fm. Determine the proton's minimum kinetic energy K less than or equal to delta K according to the uncertainty principle if the proton is well approximated by a Gaussian wave packet confined by the nuclear diameter...
4. ### Normalization Constant A

Homework Statement The wave function of a particle is Y(x,t) = A e^-kx*e^-iwt for x greater than or equal too 0, and it is zero everywhere else. What is the numerical value of the normalization constant A for k=5.55 1/nm and w =7.19 1/ps? Homework Equations intergral Y^2=1 The...
5. ### Crazy dude jumping on a Merry-Go-Round

Energy is being lost because energy is required to make the mans speed the same speed as the merry-go-round. But thank you for your input.
6. ### Crazy dude jumping on a Merry-Go-Round

True Mentz144 but the Final KE does not equal the Initial KE. I finally figured it out. my KEi was right but I added masses when finding the new MoI not m*r^2 to the MoI of the disk.
7. ### Crazy dude jumping on a Merry-Go-Round

I guess Im not because thats still the wrong answer
8. ### Crazy dude jumping on a Merry-Go-Round

So I did KEi= .5*Imgr*Wmgr^2 + .5*Ip*Wp^2 and got 5.4524 kJ then i did KEf= .5*(M1+M2)*r^2*.5*Wf^2 and got 3.559kJ Am I even close?
9. ### Crazy dude jumping on a Merry-Go-Round

So I must include the guy running although hes not on the merry-go-round yet?
10. ### Crazy dude jumping on a Merry-Go-Round

the edge of the merry go round is moving at 11.336 m/s much fast then the man. So the merry-go-round slows down. I did conservation of momentum. Initally... Lmgr= I*w= 2310.58 Lp=I*(v/r)=623.326 Ltot= 2933.9 using this I found the angular speed of the merry-go-round fonal 2933.9/(Imgr...
11. ### Crazy dude jumping on a Merry-Go-Round

No the disk is the only thing that has KE? Maybe there is something I am just not understanding about this disk.
12. ### Crazy dude jumping on a Merry-Go-Round

Homework Statement A disk-shaped merry-go-round of radius 2.63 m and mass 155 kg rotates freely with an angular speed of 0.686 rev/s. A 59.4 kg person running tangential to the rim of the merry-go-round at 3.99 m/s jumps onto its rim and holds on. Before jumping on the merry-go-round, the...
13. ### Crane lifting crate

Homework Statement The crane shown in the drawing is lifting a 186-kg crate upward with an acceleration of 2.0 m/s2. The cable from the crate passes over a solid cylindrical pulley at the top of the boom. The pulley has a mass of 130 kg. The cable is then wound onto a hollow cylindrical drum...
14. ### Walking on a canoe, finding its mass.

I did the following... Mc=Mass canoe Mp=Mass person 4.45= distance from shore+half distance of canoe Cm=Cm (Mc+Mp)*4.45/(Mc+Mp)=Cm Cm=4.45m 4.45=3.4Mp+5.35Mc/(Mp+Mc) 4.45Mp+4.45Mc= 3.4Mp+5.35Mc 1.05Mp=.9Mc 1.1667Mp=Mc Mc= 71.983kg Is this correct? or am I not suppose to assume...
15. ### Walking on a canoe, finding its mass.

I thought of that a realized I don't know how to go about it being a center of mass problem. The only thing I really undestand is its the sum of the mass*d/total mass of the system. In this case I don't know what distances to use. Distance from the shore? Distance from the center of the...
16. ### Walking on a canoe, finding its mass.

Homework Statement A 61.7 kg canoeist stands in the middle of her canoe. The canoe is 3.9 m long, and the end that is closest to land is 2.5 m from the shore. The canoeist now walks toward the shore until she comes to the end of the canoe. Suppose the canoeist is 3.4 m from shore when she...
17. ### Elastic non head on Collision

no its just the angle the He nucleus makes with respect to the x axis.
18. ### Elastic non head on Collision

'2 was suppose to be theta 2
19. ### Elastic non head on Collision

Homework Statement A neutron collides elastically with a helium nucleus (at rest initially) whose mass is four times that of the neutron. The helium nucleus is observed to rebound at an angle Theta2 = 45° from the neutron's initial direction. The neutron's initial speed is 6.6x 10^5 m/s...
20. ### Raising a Bucket out of a Well

yep that will do it, thanks.
21. ### Raising a Bucket out of a Well

Homework Statement You raise a bucket of water from the bottom of a deep well. If your power output is 104 W, and the mass of the bucket and the water in it is 6.00 kg, with what speed can you raise the bucket? Ignore the weight of the rope. Homework Equations P=W/t W=P*t...
22. ### Electron in an electirc field.

I figured out what I was doing wrong. It was in Joules and I needed to convert to Volts.
23. ### Pair-Production problems

Homework Statement How much photon energy would be required to produce a proton-antiproton pair? Give the answer in SI units. Homework Equations E^2=p^2c^2+m^2c^4 E=pc+pc p=mc E=2*m*c^2 The Attempt at a Solution I seem to be confused I know the KE would be zero I also know this...
24. ### Electron in an electirc field.

Homework Statement Across what potential difference does an electron have to be accelerated in order to reach speed v=1.80×106 m/s? Homework Equations I checked to see if relitivity was important and it was not E=.5 m v^2=eV The Attempt at a Solution I dunno if I am...
25. ### Meteorite falling on a Car

Isn't the force equal but opposite?
26. ### Bicycle coasting up a Hill

I relized i posted that wrong but the answer comes out to -487 the right way but thats the wrong answer. I edited and wrote everything out.
27. ### Meteorite falling on a Car

Homework Statement A 27 pound meteorite fell and struck a car, creating a dent about 28 cm deep. If the initial speed of the meteorite was 530 m/s, what was the magnitude of the average force exerted on the meteorite by the car? Homework Equations Vf^2=Vi^2+2ad F=ma The Attempt at...
28. ### Bicycle coasting up a Hill

Homework Statement Coasting along at 7.10 m/s, a 60.0 kg bicyclist on a 7.60 kg bicycle encounters a small hill. If the speed of the bicyclist is 6.00 m/s at the top of the hill, how much work was done on the bicyclist and her bike? Homework Equations KEf-KEi=W .5mvi^2-.5mvf^2...
29. ### How much ice must melt at 0 deg. C to gain 5 g of mass?

Someone suggested something to me and i tried it and it worked. E=mc^2 E=.005 kg* (3.0x10^8)^2. Thats the energy (in Joules) needed so take that convert it to cal and divide by the Latent Heat Fusion. Thatwill give you the # of grams. Hope this helps.
30. ### Exact Values

Sin is the y value so on a unit circle and why is negitive in quadrants 3 and 4. so at 240 deg and 300deg it should be that value.