The wạlls of ạn ice chest ạre mạde of 2.00-mm-thick insulạtion hạving ạ thermạl conductivity 0.00300 W/m∙K. The totạl surfạce ạreạ of the ice chest is 1.20 m². The temperạture of the outside surfạce of the chest is 20.0 °C. The lạtent heạt of fusion of wạter is 334 kJ/kg.

How mạny hours (time) does it tạke to melt 4.00 kg of ice plạced inside the ice chest?

A solid, uniform disk of radius 0.250 m and mass 60.6 kg rolls down a ramp of length 4.80 m that makes an angle of 12.0° with the horizontal. The disk starts from rest from the top of the ramp.

(a) Find the speed of the disk's center of mass when it reaches the bottom of the ramp.
m/s

(b) Find the angular speed of the disk at the bottom of the ramp.
rad/s

A nonconducting ring of radius of 11.6 cm is uniformly charged with a total positive charge of 10.0 µC. The ring rotates at a constant angular speed 18.6 rad/s about an axis through its center, perpendicular to the plane of the ring. What is the magnitude of the magnetic field on the axis of the ring 5.00 cm from its center?
pT

A charge of 2.20 µC is uniformly distributed on a ring of radius 9.0 cm. Find the electric field strength on the axis at the following locations. (be careful calculating c and d the last post was wrong. please include e.)

(a) 1.2 cm from the center of the ring
  N/C

(b) 3.9 cm from the center of the ring
  N/C

(c) 4.0 m from the center of the ring
  N/C

(d) Find the field strength at 4.0 m using the approximation that the ring is a point charge at the origin.
  N/C

(e) Compare your results for parts (c) and (d) by finding the ratio of the approximation to the exact result.


(f) Is your approximation result a good one? Explain your answer. (Do this on paper. Your instructor may ask you to turn in your work.)

Explain how X-ray observations are used to determine the temperature, T (r), and den- sity, ρgas, of the hot gas in an elliptical galaxy. What quantities are observed directly and how are they used to ultimately determine T and ρgas?

Ilya and Anya each can run at a speed of 8.30mph and walk at a speed of 3.90mph . They set off together on a route of length 5.00miles . Anya walks half of the distance and runs the other half, while Ilya walks half of the time and runs the other half.

How long does it take Anya to cover the distance of 5.00miles ?

Express your answer numerically, in minutes.

Find Anya's average speed.

Express Anya's average speed save,Anya numerically, in miles per hour.

How long does it take Ilya to cover the distance?

Express the time tIlya taken by Ilya numerically, in minutes.

Now find Ilya's average speed.

Express Ilya's average speed save,Ilya numerically, in miles per hour.

A mass (m) with speed (v) experiences a perfectly elastic collision with an initially stationary mass (M). What is the ratio of the masses (m/M) if after the collision, m and M have the same speed (V) but opposite velocities?

A nonconducting sphere 1.6 m in diameter with its center on the x axis at x = 4 m carries a uniform volume charge of density ρ = 5.4 µC/m³. Surrounding the sphere is a spherical shell with a diameter of 3.2 m and a uniform surface charge density σ = -2 µC/m². Calculate the magnitude and direction of the electric field at the following locations.

(a) x = 4.7 m, y = 0
  N/C î +   N/C ĵ

(b) x = 4 m, y = 1.5 m
  N/C î +   N/C ĵ

(c) x = 2.0 m, y = 3.0 m
  N/C î +   N/C ĵ

(please be careful with b and c last post was wrong

A 2.90-kg box is sliding along a frictionless horizontal surface with a speed of 1.8 m/s when it encounters a spring.

(a) Determine the force constant of the spring, if the box compresses the spring 5.30 cm before coming to rest.

(b) Determine the initial speed the box would need in order to compress the spring by 1.50 cm.

Carla and Jenny are arguing about whether or not it is possible to escape the gravitational field of the Earth. Carla shows Jenny a system where mass m is r_E (not the Earth's radius) distant from Earth and r_P (not planet P's radius) distant from planet P, the mass being on the line connecting the Earth and planet P. Carla states that the mass m has escaped if F_{P on m} = −F_{E on m}. Jenny disagrees. Which one, if either, is correct, and why?

How much energy is required to change a 60 g ice cube from ice at -25

The speed of sound is finite. This means that it has a specific, distinct speed, that we can calculate. Explain an every day example of how we know that the speed of light is finite.

Blocks with masses of 3.0 kg, 4.0 kg, and 5.0 kg are lined up in a row on a frictionless table. All three are pushed forward by a 19N force applied to the 3.0 kg block.

a) How much force does the 4.0 kg block exert on the 5.0 kg block?

b)How much force does the 4.0 kg block exert on the 3.0 kg block?

please explain! thanks!

What is the theoretical minimum frequency a photon must have in order to create a photoelectron? Show work to support your answer.

One of the difficulties of the Bohr model was that it assumes the existence of stationary orbits. Why was this problematic from a classical physics point of view? How does the solution of the Schrödinger equation remedy this situation?