Explain in terms of the location of the center of mass, the physical reason why you begin to fall forward when you lean forward far enough.

Light from a fluorescent lamp is observed through a cloud of cool nitrogen gas. Again, two students are having a discussion about the kind of spectra that they would see.

Student 1: We would see absorption line spectra and the missing lines would correspond to the light from the fluorescent lamp.

Student 2: I disagree. We would see an emission line spectrum corresponding to nitrogen. This would happen because the nitrogen gas would absorb some energy from the fluorescent lamp and would reemit this energy which would result in an emission line spectrum.

**** Which student, if any, do you agree with and why?

The frequency of light reaching Earth from a particular galaxy is 18% lower than the frequency the light had when it was emitted. a) explain whether the galaxy is moving toward or away from earth. b) What is the speed of this galaxy relative to the Earth? Give your answer as a fraction of the speed of light.

10 kg crate is pulled 4.9 m up a 34 degree incline by a rope angled 16 degree above the incline. The tension in the rope is 125 N, and the crate's coefficient of kinetic friction on the incline is 0.26.
How much work is done by:
a. Tension? J

b. Gravity? J

c. Normal Force? J

d. What is the increase in thermal energy of the crate and incline?

J

1. (i)Use the Huygens principle to explain how plane parallel wavefronts are diffracted at a single aperture.

2. (ii) Use the principle of superposition to explain how coherent light emerging from two narrow slits can interfere to produce a pattern on a distant screen.

Why is that the masses for proton and neutron more precisely measured in atomic mass units (u) than in megaelectron volts (MeV)?

A truck with a total mass of 1.72 * 10^3 kg has wheels of radius 33.0 cm and moment inertia of 0.800kg-m^2. Find the trucks (a) translational energy and (b) rotational energy when the truck is moving at a speed of 25.0 m/s

Show All Your Work

Describe rotational motion (angular displacement, angular velocity, angular acceleration, torque, moment of inertia, etc.). Use equations and words.

If you get a negative impulse, does this mean you lost momentum? I know Impulse=change in momentum. Ex) A ball hits a wall and leaves the wall with a lower velocity than when it hit. Is momentum conserved?

Water to a residential area is transported at a rate of 1.5 m³/s via 70-cm-internal-diameter concrete pipes with a surface roughness of 3 mm and a total length of 1520 m. In order to reduce pumping power requirements, it is proposed to line the interior surfaces of the concrete pipe with 2-cm thick petroleum-based lining that has a surface roughness thickness of 0.04 mm. There is a concern that the reduction of pipe diameter to 66 cm and the increase in average velocity may offset any gains. Taking ρ = 1000 kg/m³ and v = 1 × 10^–6 m²/s for water, determine the percent increase or decrease in the pumping power requirements due to pipe frictional losses as a result of lining the concrete pipes. (Round the final answer to one decimal place.)

What is the wavelength of the -Hz radio wave used by “radio-controlled” clocks and wristwatches?​

(Explain using the law of conservation of momemtum)   When a ball strikes the floor and rebounds, it appears that momentum is not conserved. Is this true? Why or why not?

A 120 kg crocodile swallows gastrolithes that are 0.8% of his mass to sink to a lower level. How much would it have to increase its lung volume in mL to counteract the sinking effect? Assume that the air pressure in its lungs is not much greater than atmospheric pressure.

The 25-lb slender rod has a length of 6 ft. Using a collar of negligible mass, its end A is confined to move along the smooth circular bar of radius 32√ ft. End B rests on the floor, for which the coefficient of kinetic friction is μB = 0.28. The bar is released from rest when θ = 30∘.

Determine the angular acceleration of the bar at this instant, measured clockwise.

A 60 kg sofa 4m long is carried by James and Sarah. James is holding the sofa 0.2m from an end. Sarah is holding the sofa by the other end. A passing moron places a 40 kg box of books on the sofa 0.5m from the end Sarah is holding. How much weight is sarah holding now.