- #1
vabamyyr
- 66
- 0
bullet enters a wall with speed v1 and goes out with speed v2, the wall is h units thick. During that time it experiences an impending force which is proprtional to v^2. I have to find the time the bullet goes out the wall.
I can take t0=0 v0=v1 x0=0
Using N2 law i get d(mv)/dt = -F.....mdv/dt = -m*v^2 (im not sure if I am missing here something)
dv/dt = -v^2
dt = - dv/v^2 ===> t = (v1-v2)/v1*v2...this result is weird since it doesn't contain h so i must have constructed the equation wrongly i guess.
I think that F depends on h since F can act only between [0; h], and maybe the answer should be multiplied with h and t = h*(v1-v2)/v1*v2...but it still doesn't look right to me...any opinions?
I can take t0=0 v0=v1 x0=0
Using N2 law i get d(mv)/dt = -F.....mdv/dt = -m*v^2 (im not sure if I am missing here something)
dv/dt = -v^2
dt = - dv/v^2 ===> t = (v1-v2)/v1*v2...this result is weird since it doesn't contain h so i must have constructed the equation wrongly i guess.
I think that F depends on h since F can act only between [0; h], and maybe the answer should be multiplied with h and t = h*(v1-v2)/v1*v2...but it still doesn't look right to me...any opinions?