Answer to Question 1

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  (a)  What is the most probable speed?  

 

The most probable speed is 9.0 m s-1 because there are the most molecules (4) travelling at that speed.

 

                                              

 (b) What is the mean speed?

     

There are 10 molecules:

 

Mean speed = (1 5.0) + (2 7.0) + (4 9.0) +  (1 12.0) +  (1 14.0) +  (1  15.0)                                                                       

                                                                           10

 

                = 5 + 14 + 36 + 12 + 14 + 15 = 96 = 9.6 m s-1

                                        10                       10 

 

  (c) What is the rms speed of the molecules?

  

Mean square speed = 25 + 98 + 324 + 144 + 196 + 225 = 1012

                                                   10                                        10   

= 101.2 m2 s-2 

 

Rms speed = 101.2 = 10.1 m s-1