A few physics questions.. help!?

Question

1. a cricket ball of mass 150g is travelling at 150km/h. if it collides with an 4kg cricket bat in an elastic collision travelling in the opposite direction at 10m/s, what would be the resultant velocity of the cricket ball if the bat continues at 1m/s.

2. a 2kg ball (A) travelling west at 6m/s collides with another ball (b) of mass 2.5kg. Ball B moves west at 3m/s.

a) Calculate the velocity of ball A

b) Was the collision elastic or inelastic?

Answer 1

These questions are the reason why I only just passed physics.

Answer 2

1) first convert the mass of the cricket ball and its speed into kg ans m/s.

           mass = 0.15kg

           speed = 41.67m/s

because this is an elastic collision the momentum of  the two systems (before and after collision) is conservative:

therefore:  to the east direction

momentum before collision = momentum after collision

(0.15 x 41.67) - (4 x 10) = -(0.15 x V) - (4 x 1)

6.25 - 40   =  -0.15V - 4

6.25 - 40 + 4 = - 0.15V

-29.75       = -0.15V

V        = -29.75 / -0.15

V        =  198.33 m/s...........sorry,but this is the ans i got!!

2) a) to the west direction

momentum before collision = momentum after collision

(2 x 6) + (2.5 x 0) = (2 x V) + (2.5 x 3)

12 = 2V + 7.5

12 - 7.5 = 2V

V = 12 - 7.5 / 2

V = 2.25 m/s

b) if the collision is elastic then KE too is conservative:

(2 x 6 x 6 / 2) + (2.5 x 0 / 2) = (2 x 2.25 x 2.25 / 2) +  (2.5 x 3 x 3 / 2)

36 = 4.5 + 11.25

36 = 15.75...............( KE is not conservative)

this is an inelastic collision.

Answer 3

and to think i was gona pick physics

im sorry i really cant help u my brain hurts had tests all day and now this haha good luck yea  google mayb?

or jus ask ur teacher at school