8. You begin to get tired and the book begins to slide down. The book begins to slide down, and you respond so it slides down at a constant velocity. How do each of the forces you have identified change from their magnitudes in part (a)? Explain how you know. (this question will not be auto-graded, answer fully)

9. If the book has a mass of 2 kg, the coefficient of friction between the sliding book and the wall is 0.4, how hard do you have to press on the book if it is sliding down with a speed of 2 cm/s? D2M

10. BCD on 9

One non-powered sled is sliding over a snowed surface, first down from the top of a flat and inclined plane using only gravity and no initial speed and then it continues to move along a horizontal surface until a full stop. The plane’s surface is inclined with 45 degrees relative to the horizontal. The top of the inclined plane is 2 meters high relative to the same horizontal surface. The friction coefficient between the sled and snow is 0.05 on all surfaces. Draw the free-body diagrams and determine the formula and the value for the distance made by the sled onto the horizontal surface.

Draw the Free-body diagrams as well

Identify the synthesis method that has the best chance to yield nanoparticles of a uniform size. For comparison, also identify which method we covered that you believe is the least likely to yield uniformly sized particles. Explain your reasoning for selecting these two.

Think of a Newtonian cradle made of only two marbles. These two marbles of masses m1 and m2 are each suspended by identical strings. The strings are initially both vertical so the marbles are touching each other when undisturbed. The marble with m1 is shifted away from the initial position until is reaching the height h1 while the length of the string does not change and then is set free to fall and collide with marble m2. What is the formula for the height which both marbles will reach after the collision if: a). The collision is elastic; b). The collision is inelastic; (c). What will be the heat developed during the collision in both cases?Hint: when the marbles collide, all vectors velocity are orientated along the same axis.

Draw diagrams as well

Assume a galaxy forms its stars in a single rapid burst, with a Salpeter initial mass function extending from 0.1 to 100 Msun. After 10 Gyrs have passed, divide the surviving stars into three groups: lower main-sequence upper main sequence (MS stars with mass > 0.75 Msun), lower main sequence (MS stars with mass < 0.75 Msun), and red giants. Calculate the fractional contribution of each group to: 


(a) the total number of surviving stars. (b) the total mass in surviving stars. (c) the total luminosity of the galaxy.

Hints: Assume the MS lifetime-vs-mass relation and RGB lifetimes as given in Lecture I. Ignore post-RGB evolutionary stages. For MS stars, assume luminosity-mass relation of (L/Lsun) = (M/Msun)3.5. Assume (crudely) that the average RGB luminosity is ~100 times higher than the turn-off luminosity. 


Light of wavelength 600 nm passes though two slits separated by 0.25 mm and is observed on a screen 1.3 m behind the slits. The location of the central maximum is marked on the screen and labeled y = 0.

A .At what distance, on either side of y = 0, are the m = 1 bright fringes?

B.A very thin piece of glass is then placed in one slit. Because light travels slower in glass than in air, the wave passing through the glass is delayed by 5.0 ×10?16s in comparison to the wave going through the other slit. What fraction of the period of the light wave is this delay?

C. With the glass in place, what is the phase difference ??0 between the two waves as they leave the slits?

D. By how far does the central maximum move?

An initially uncharged hollow metallic sphere with radius of 5 cm has a small object with a charge of +10 mC carefully placed at the center of the sphere through a hole in the latter's surface. With the charge in place, what charge is now present on the outside surface of the sphere? I know the answer 10uC, but do not understand how to get there. Please show work.

You bungee jump from a point 50 [m] off the ground with a mass of 75 [kg] using a bungee cord with an unstretched length of 16 [m] and a spring constant of 55 [N/m]. Will you hit the ground and at what speed? If you will not hit the ground, how close to the ground do you come to a stop?

Some people believe that the Moon controls their activities. The Moon moves from being directly on the opposite side of Earth from you to be being directly overhead. Assume that the Earth-Moon (center-to-center) distance is 3.82 ✕ 108 m and Earth's radius is 6.37 ✕ 106 m. (a) By what percent does the Moon's gravitational pull on you increase? % (b) By what percent does your weight (as measured on a scale) decrease?

A pendulum consists of a stone with mass m swinging on a string of length L and negligible mass. The stone has a speed of v₀ when it passes its lowest point. (a) Write an expression for the speed of the stone when the string is at some angle theta with the vertical. (b) What is the greatest angle with the vertical that the string will reach during the stone's motion? (c) If the potential energy of the pendulum-Earth system is taken to be zero at the stone's lowest point, what is the total mechanical energy of the system? State all your answers in terms of the given variables and g.

Q.2: (i) Express ‘Uncertainty Principal’ briefly.

(ii) In the Davisson-Germer Experiment, what will be Bragg Scattering angle (first order) for an electron-beam when diffracted from the surface of Ni-crystalwith atomic-planes spacing D= 0.215 nm and the kinetic energy of the e-beam is approximately 75 eV.

iii. Qualitatively, discuss how the angle will change if the voltage is doubled.

A solid steel sphere of radius 1.50cm and density of 8045 kg/m³ was launched on a horizontal frictionless surface. The sphere was launched using a spring gun which possessed a spring with a force constant of 35.6 N/m. The spring was compressed 30.0 cm and the sphere was launched. At the end of the frictionless surface (that was 0.955 m above the floor), the sphere rolled (no slipping) up a 25° ramp with height of 1.15m and then launched off of the ramp. The coefficient of rolling friction between the sphere and ramp was 0.0500. What was the speed of the sphere at the end of the frictionless surface (when it was sliding - not rolling) ? What was the translational speed of the sphere at the very beginning of the ramp (when it transitioned to perfect rolling (no slipping))? What was the sphere's rotational speed (in revolutions per minute) at the very top of the ramp? Ignoring drag, at what horizontal distance from the end of the ramp did the sphere strike the floor? What was the greatest height the sphere achieved (above the floor)?

at what time stamp

where does the repeat of the exposition start in the recording of beethoven sympothy 5

A 2.0 mm -diameter, 50 cm -long copper wire carries a 4.5 A current. What is the potential difference between the ends of the wire?