this kinda sucked damn big time cause my differentiation is atrocious.
and so i need help
newton's second law states that force on an object is given by the rate of change in its momentum correct?
if i expand dp, i get dmv.
then now, i got to break up dmv. i'll let dt go over to F part.
now here is the part that i screw up. wads m and wads v?
i'll throw in some numbers so u all can punch. i got weird values.
assuming a car is travelling initially at 10ms-1, with the mass of the car+fuel being 100kg.
at time 1s later, the car is travelling at 100ms-1, with the mass of car + fuel being 10kg.
what is the force acting on the car during this 1s?
if i take it as Fdt= change of momentum, then i punch in numbers...
i shld get 0 resultant force as the momentum m1v1=m2v2 and hence no force.
yet if u use mdv+vdm.....
100kg (100-10)+ 10ms-1 (10-100)
u get a weird value.
i suspect i punched in wrong numbers for V and M. or my DV and DM is wrong. anyone can advise?