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mechanics 2

so ive just started learning m2 buy my teacher is awful, shes given us a few question but i have no clue what to do

a ball mass 0.4kg is fired horizontally 350m/s. it hits a target penetrating for 0.25m before coming to rest, using the work energy principle find the resistive force of the target

Reply 1

the bear

well you need to let the kinetic energy of the ball equal the work done against the resistance of the target

KE = .5mv²

work done = Force * Distance

Reply 2

printergirl

Original post by the bear

well you need to let the kinetic energy of the ball equal the work done against the resistance of the target

KE = .5mv²

work done = Force * Distance

how do i get the force of this? 'f=ma' i dont know acceleration

edit
do i do 245000=f x 0.25

(edited 11 years ago)

Reply 3

TenOfThem

Original post by printergirl

edit
do i do 245000=f x 0.25

yes

Reply 4

printergirl

Original post by TenOfThem

yes

so answer is 98000 N, this seems very large!

Reply 5

TenOfThem

Original post by printergirl

so answer is 98000 N, this seems very large!

Well

It was going very fast

And it did have to stop pretty quickly

So a big force would be needed

Reply 6

the bear

350 m/s is 790 miles per hour....

Jumbo Jets cruise at 250 m/s

none of the Fighter Planes in WWII exceeded 690 miles per hour:

http://www.militaryfactory.com/aircraft/ww2-aircraft-ranked-by-speed.asp

(edited 11 years ago)