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?

As the temperature of a metal rod varies, so does the resistance and the dimensions of the rod. If a copper rod has a resistance of 4.78 Ω at 20.0°C, determine the resistance of the rod (in Ω) at 120°C by accounting for the changes in both the resistivity and the dimensions of the rod. The coefficient of linear expansion for copper is 1.67 ✕ 10−5 (°C)−1 and the temperature coefficient of resistivity is 4.04 ✕ 10−3 (°C)−1.

Snell's Law and the Law of Reflection explain how light is redirected when it encounters a surface between two media. In the extreme, light may only reflect at a boundary, and go back into the medium it was in. More often, some of it reflects and some goes through. If the boundary is plane and flat, then these laws are easy to interpret. When the boundary is curved, they describe happens at every point on the surface. One of the classic types of glass is called "crown" glass, which has an index of refraction for visible light of 1.52 and is usually free of significant impurities. It was one of the first glasses discovered, and windows are made from it. Another glass is called "flint" glass, and it has lead oxide added, which makes it heavier, more "dispersive", and increases its index of refraction to 1.62. 1. A ray of light enters a flat surface of crown glass at a 25 degree angle to the surface. At what angles do the reflected and refracted rays leave the surface? 2. As in the first part, but for flint glass, what are the angles? 3. For the flint glass, the refracted ray goes through the glass to the other side. If the glass is a parallel slab, what happens when the ray reaches the opposite side from the inside? At what angle to the surface does it exit the glass back into air? 4. What is the smallest angle to the surface that light can have and still be transmitted from the inside to the outside in the case of flint glass? What angle is the light going at as it leaves in that case? Hint: The laws of reflection and refraction are usually stated in terms of the angles to the perpendicular or "normal" to the surface. These questions are rephrased in terms of the angles to the surface so take care in interpreting the laws and your answers.

1. You have a massless, ideal spring with an unknown spring constant ?. You hang the spring from the ceiling. You then attach a mass (? = 21.0 kg) to the spring, which causes it to fall a distance of 2.75 m before stopping immediately before hitting the floor.

   (a) What is ??
   (b) Graph gravitational potential energy versus the position of the mass above the floor. (c) Graph elastic potential energy versus the position of the mass above the floor.
   (d) Graph the kinetic energy of the mass versus the position of the mass above the floor.

Suppose you’re eating in yet another restaurant where the dishes are shared at the table and all placed uniformly on a rotating disk-like surface. Model this surface as a thin disk of radius 45.3 cm. Someone else has spun the surface, such that it is initially at an angular speed of 0.4 rev/s. The surface and food has a combined mass of 3.3 kg. The waiter, to show off, throws a new dish of dumplings (mass 0.8 kg) onto the surface at a speed of 0.5 m/s, such that the dish lands on and sticks to the very edge of the surface moving in the same direction as the rotating food. While this is happening, you quickly calculate the final angular speed of the food so that you can predict its location at any time before others have a chance to eat the dumplings. What is this speed, in rad/s?

A container has a flat bottom made of aluminum that is 1.18 -cm thick. The walls are insulated with thick styrofoam. The exterior bottom of the container is in continual contact with boiling water. Inside the container, ethanol (ethyl alcohol) is boiling. How long until the alcohol completely boils away if initially it has a depth of 5 cm? Assume that the thermal conductivity of aluminum is 220 W/m· ◦C, the latent heat of vaporization of ethanol is 854 kJ/kg, the boiling point of ethanol is 78.2 ◦C, and the density of ethanol is 785 kg/m3 . [50, 80 s]

A proton is fired from far away toward the nucleus of a mercury atom. Mercury is element number 80, and the diameter of the nucleus is 14.0 fm.

If the proton is fired at a speed of 4.4

A bicycle racer sprints at the end of a race to clinch a victory. The racer has an initial velocity of 13.0 m/s and accelerates at the rate of 0.450 m/s^2 for 7.00 s.

(a) What is his final velocity (in m/s)? 16.15 m/s

(b) The racer continues at this velocity to the finish line. If he was 300 m from the finish line when he started to accelerate, how much time (in s) did he save?

(c) One other racer was 5.00 m ahead when the winner started to accelerate, but he was unable to accelerate and traveled at 13.2 m/s until the finish line. How far ahead of him (in meters and in seconds) did the winner finish?

distance m?

time s?

A spacecraft starts from rest, and makes a journey to a destination 134000 km from its starting point. It does so by accelerating at a constant rate of 8.91 m/s^2 up to the midpoint of the journey, and then decelerates at the same constant rate of 8.91 m/s^2 for the second half of the journey, ending at rest. How long did the entire journey take?

A car drives around a circular track of diameter 75 m at a constant speed of 36.0 m/s. During the time it takes the car to travel 232 degrees around, what is the magnitude of the car s average acceleration?