Other Physics Answers

Lesson Thermodynamics Processes

1. An engine bought by an engineer rated a transfer of 5,000 J of energy from a hot reservoir during one cycle and dissipated 3x10³J. Find the efficiency of the engine.

2. A particular heat engine has a mechanical power output of 5.00 kW and an efficiency of 25.0%. The engine expels 8.00x10³ J of exhaust energy in each cycle. Find (a) the energy taken in during each cycle and (b) the time interval for each cycle

The density of air at standard conditions (p = 1 atm and t = 20°c) is 1.28 kg/m³. At what pressure is the density 0.64 kg/m³ if the temperature and number of molecules are kept constant?

Household Experiment - Cooling a Balloon

Inflate a balloon at room temperature. Leave the inflated balloon in the refrigerator or in an ice bucket half-filled with ice overnight. What happens to the balloon and why? Then illustrate/draw what happens to the balloon before leaving it in the refrigerator overnight and after leaving it overnight.

How much work is done by 15 kW engine during 3.5 min?

A wind turbine can generate 150W on average and costs £3000 to buy and install What is the cost per kWh if the owner wants to pay for the turbine with five year's electricity sales? Give your answer as a number of pence to the nearest penny

In an experiment to determine the energy stored in a stretched spring, a spiral spring was suspended from a properly mounted retort stand. A mass hanger was suspended on the free end of the spring and different masses added to the hanger. The hanger was gently pulled backwards and released to set I into vertical oscillations. For each mass, the average time for ten vibrations was taken and presented as shown in the data below.

MASS(g) Averagetimetaken for ten

50.0 5.80

70.0 6.80

90.0 7.80

110.0 8.60

130.0 9.20

Period,T(s)

T2(*10-3 s)

State the number of significant figures in each of the following numbers and explain your answer

(I) 37.60 (Ii) 0.0130 (III) 13000 (iv) 1.3400

From the definition of the divergence, obtain an expression for ∇.F in cylindrical coordinates

The vectors from the origin to the points A, B,

C and D are A= i + j + k

B = 2i +3j

C= 3i + 5j -2k

D = k- j

Show that the lines AB and CD are parallel and find the ratios of their lengths

Show that the unit vector normal to the surface φ (r) = constant is n= ∇φ ÷ | ∇φ |

Find n for the ellipsoid.

φ = a(x^2) + b(y^2) +c(z^2)