Explanation:
V=u+at
where,
v=final speed
u=initial speed,(starting speed)
a=acceleration
t=time
- v=u+at = 6=2+a*2
 6=2+2a
 2a=6-2
 2a=4
 a=4/2 = 2
a =2
2. to find time taken 
 v=u+at
 25=5*2t
 2t=25-5
 2t=20
 t=20/2
t=10sec
3. finding final speed
v=u+at
v=4+10*2
=4+20
v=24m/sec
5.v=u+at
=5+8*10
=5+80
V=85m/sev
6. v=u+at
 8=u+4*2
 8=u+8
 U=8/8
u=1
these are your missing values
 
        
             
        
        
        
Let the unknown distance be xmiles
x/39-x/72=11hr
72x-39x/2808=11hr
33x/2808=11
33x= 30888
x=936miles 
U can substitue back to check
at speed of 72mph, he would need 936/72=13hrs
at speed of 39mph, he would need 936/39=24hr
the difference is 24-13=11
        
             
        
        
        
Density = mass / volume ;
1 Cubic Centimeter = 0,000001 Cubic Meter
8 cm^3 = 0.000008 m^3
12,9 g = 0,0129 kg
The density is 0,0129 kg/ 0,000008 m^3 = <span><u>1612,5 kg/m^3</u> </span>
        
             
        
        
        
The answer to your question Tropical Cyclones