Questions and Answers of The Physics Energy

Estimate the power output of an elite cyclist pedaling a bicycle on a flat road at 14 m/s. Assume all energy is lost to air resistance, the cross-sectional area of the cyclist and the bicycle is 0.4
Consider an airplane with mass 70 000 kg, cross sectional area 12 m2, and drag coefficient 0.03. Estimate the energy needed to get the plane moving at 800 km/h and lift the plane to 10000 m, and
The density of air decreases with altitude roughly as ρ ∼ ρ0e−z/H, where z is the height above the Earth’s surface and H ≅8.5 km near the surface. Compute the ratio of air resistance losses
Consider a collision between two objects of different masses M,m moving in one dimension with initial speeds V, −v. In the center-of-mass frame, the total momentum is zero before and after the
Verify the claim that conversion of the potential energy at the top of a 15 m hill to kinetic energy would increase the speed of the Toyota Camry from 62 to 74 mph.
Relate eq.(2.20)?? to eq. (2.9) and compute g in terms of G, M?, R? as described in the text. GMm V (r) =
Estimate the potential energy of the international space station (mass 370000 kg) relative to Earth’s surface when in orbit at a height of 350 km. Compute the velocity of the space station in a
An object of mass m is held near the origin by a spring, F = −kx. What is its potential energy? Show that x(t) = (x0, y0, z0) cos ωt is a possible classical motion for the mass. What is the energy
A mass m moves under the influence of a force derived from the potential V(x) = V0 cosh ax , where the properties of cosh x, What is the force on the mass? What is the frequency of small
Estimate the kinetic energy of the ocean liner Queen Mary 2, with mass (displacement) 76000 tons, moving at a cruising speed of 26 knots. Compare with the change in potential energy of the Queen Mary
Use any means at your disposal (including the internet) to justify estimates of the following: (a) The kinetic energy of the Moon in its motion around Earth. (b) The kinetic energy of a
Choose your favorite local mountain. Estimate how much energy it takes to hike to the top of the mountain (ignoring all the local ups and downs of a typical trail). How does your result compare to a
Make a rough estimate of the maximum hydropower available from rainfall in the US state of Colorado. Look up the average yearly rainfall and average elevation of Colorado and estimate the potential
The US total electrical power consumption in 2010 was 3.9 TkWh. Utilities try to maintain a capacity that is twice the average power consumption to allow for high demand on hot summer days. What
The energy available from one kilogram of 235U is 82 TJ. Energy is released when each uranium nucleus splits, or fissions. (The fission process is described in §16, but you do not need to know
The energy emitted or absorbed in chemical processes is often quoted in kilo joules per mole (abbreviated mol) of reactants, where a mole contains NA ≅ 6.022 x 1023(Avogadro’s number) molecules
The gravitational potential energy of an object of mass m at a distance h above ground is given by E = mgh . Use dimensional analysis to compute the units of g. What does this result suggest about
The US total energy consumption in 2014 was 98.0 quads. What is this quantity in joules? About 83% of US energy comes from fossil fuels. If the whole 83% came from oil, how many tons of oil
In a typical mid-latitude location, incident solar energy averages around 200 W/m2 over a 24-hour cycle. Compute the land area needed to supply the average person’s energy use of 200 MJ/day if
How much energy would a 100 W light bulb consume if left on for 10 hours?
Confirm eq.and the estimate for the rhinoceros’s kinetic energy below eq. by explicit calculation. Ep+p=2MPC² = 3 x 10-10 JE 1877 MeV. kinetic energy = mv²

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