# Bong Ro

Topics: Energy, Coal, Energy development Pages: 59 (8803 words) Published: August 23, 2013
IB Questionbank Physics

Energy, Power and Climate

1.

In which of the following places will the albedo be greatest? A. B. C. D. A forest A grassland An ocean A polar ice cap (Total 1 mark)

2.

A spherical black body has absolute temperature T1. The surroundings are kept at a lower absolute temperature T2. What is the net power per unit area lost by the body? A. B. C. D. σT14 σT24 σ(T14 – T24) σ(T14 + T24) (Total 1 mark)

IB Questionbank Physics

1

3.

What is the unit of surface heat capacity? A. B. C. D. J kg–1 K–1 J K–1 J m–2 K–1 J m–3 K–1 (Total 1 mark)

4.

Surface X has a temperature TX and emissivity εx. Surface Y has a temperature TY and emissivity εy. The two surfaces emit radiation at the same rate. What is the ratio

TX ? TY

1

A.

εy  ε  x
εx  εy 
εy  ε  x εX   εy 

4   
1

B.

4   
       
4

C.

4

D.

(Total 1 mark)

IB Questionbank Physics

2

5.

Large areas of rainforests are cut down and burned every year. The result of these actions is A. B. C. D. reduced albedo. reduced carbon fixation. increased evaporation rate. increased mass of atmospheric methane. (Total 1 mark)

6.

Simple harmonic motion and the greenhouse effect (a) A body is displaced from equilibrium. State the two conditions necessary for the body to execute simple harmonic motion. 1. ......................................................................................................................... ......................................................................................................................... 2. ......................................................................................................................... ......................................................................................................................... (2)

IB Questionbank Physics

3

(b)

In a simple model of a methane molecule, a hydrogen atom and the carbon atom can be regarded as two masses attached by a spring. A hydrogen atom is much less massive than the carbon atom such that any displacement of the carbon atom may be ignored. The graph below shows the variation with time t of the displacement x from its equilibrium position of a hydrogen atom in a molecule of methane.

The mass of hydrogen atom is 1.7 × 10–27 kg. Use data from the graph above

(i)

to determine its amplitude of oscillation. ......................................................................................................................... (1)

(ii)

to show that the frequency of its oscillation is 9.1 × 1013 Hz. ......................................................................................................................... ......................................................................................................................... (2)

IB Questionbank Physics

4

(iii)

to show that the maximum kinetic energy of the hydrogen atom is 6.2 × 10–18 J. ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... (2)

(c)

On the grid below, sketch a graph to show the variation with time t of the velocity v of the hydrogen atom for one period of oscillation starting at t = 0. (There is no need to add values to the velocity axis.)

(3)

(d)

Assuming that the motion of the hydrogen atom is simple harmonic, its frequency of oscillation f is given by the expression f= 1 2π k , mp

where k is the force per unit displacement between a hydrogen atom and the carbon atom and mp is the mass of a proton. (i) Show that the value of k is approximately 560 N m–1....

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