Physics Answers

2. The latent heat of the water-steam phase transition at p=1 atm and T=100^oC is 2256 kJ/kg. What is the entropy change delta S as the liquid vaporizes?

A. –22.56 kJ/K-kg

B. -6048 J/K-kg

C. 6048 J/K-kg

D. 22.56 kJ/K-kg

1. IN YOUR OWN WORDS, what do you think is the biggest role of telescopes in Modern Astronomy?

The orbital period of Planet A is 16 years and its average distance to Star B is 5.25 a.u. Another planet called Planet C has an average distance of 10.3 a.u. from Star B, using Kepler’s Third Law of Planetary Motion, compute the orbital period of Planet C to Star B in days.

A car mass 1.0x105g travelling at 20m/s is brought to rest by applying the brakes. Assuming that the kinetic energy of the car becomes transferred to internal energy in four steel brake drum of equal mass, find the rise in temperature the drum if the total mass is 20kg, the specific heat capacity of the steel is 450J/kg and the work done is equal on all four drum

10. An object is placed at a distance of 4.5 cm to the left of a convex lens A of focal

length 4 cm.

(a) Find the distance from lens A where a screen should be placed to obtain the image.

(b) The screen is removed and the image is used as an object for a diverging lens B of

focal length 2 cm so that a real image is formed at a distance of 8 cm from lens B.

Find the distance between lens A and lens B.

Find the measurement of the angle of refraction using the given illustration.

N

\ |

Air (n=1.00) \ |

\ |

_____________ \ | _____________

Crown |

Glass (n= 1.52) |

|

A 76N crate is hung from a spring (k=450 n/m).how much displacement is caused by the weight of this crate

The temperature of a body when placed in a room fell from 37⁰C to 35⁰C in 2 minutes. What is the cooling rate?

EX 5:- 1 The molecular weight of carbon dioxide, CO2

, is 44. In an experiment the value

γ for CO

2 was found to be 1.3. Assuming that CO

2

is a perfect gas, calculate the gas

constant, R, and the specific heats at constant pressure and constant volume, Cp, Cv

(0.189 kJ/kg.K; 0.63kJ/kg.K; 0.819kJ/kg.K).