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# PHYSICS questions HELP!!!, answer any of them ASAP please and thank you.........from Urbanski's class?

these are physics essays:

1.) A 28-g rifle bullet traveling 230 m/s buries itself in a 3.6-kg pendulum hanging on a 2.8-m long string, which makes the pendulum swing upward in an arc. Determine the vertical and horizontal components of the pendulums displacement.

2.) a 12-kg hammer strikes a nail at a velocity of 8.5m/s and comes to rest in a time interval of 8 ms (a.) what is the impulse given to the nail? (b.) what is the average force acting on the nail?

3.) a ball of mass .440 kg moving east (+x direction) with a speed of 3.30 m/s collides head on with a .220 kg ball at rest. fi the collision is perfectly elastic, what will the speed and direction of each ball after the collision??

multiple choice

18.) a.10 kg ball is dropped onto a table top, the speeds of That ball right before and right after hitting the table top are 4.0 m/s and 4.0 m/s, respectively. If the collision between the ball and the table top lasts .15 seconds what is the magnitude of the average force exerted on th ball by the table top?

a) .67 N

b.) 1.3 N

c.) 3 N

d.) 6 N

19.) a 2 kg softball is pitched to you at 20 m/s. you hit the ball back along the same path and at the same speed. I f the bat was in contact with the ball for .10 seconds what is the magnitude of the average force the bat exerted?

a.) zero

b.) 40N

c.) 400N

d.) 800N

6.) a 2 kg mass moves with a speed of 5 m/s. It collides head-on with a 3 kg mass at rest. If the collision is perfectly elastic, what is the speed of the masses after the collision?

a.) 10 m/s

b.) 2.5 m/s

c.) 2.0 m/s

d.) zero, since the collision is inelastic

13.) a 3 kg mass is positioned at ( 0, 8) and a 1.0 kg mass is positioned at ( 12, 0 ) . What are the coordinates of a 4.0 kg mass which will result in the center of mass of the system of three masses being located at the orgin (0, 0) ?

a.) (-3, -6)

b.) ( -12, -8)

c.) ( 3, 6)

d.) ( -6, -3)

16.) a .060 kg tennis ball initially moving at a speed of 12 m/s is struck by a racket causing it top rebound in the opposite direction at a speed of 18 m/s. What is the change in momentum of the ball?

a.) 0.36 kg*m/s

b.) 0.72 kg*m/s

c.) 1.1 kg*m/s

d.) 1.8 kg*m/s

17.) the center of mass of a two particle system is at the origin. One particle is located at (3 m, 0) and has a mass of 2 kg. What is the location of the second mass of 3 kg?

a.) (-3m, 0)

b.) (-2 m, 0)

c.) (2m , 0)

d.) (3m , 0)

### 1 Answer

- 1 decade agoFavorite Answer
heyy!!.. okay u r in my class! and i found this by looking for number 3... but for number 16 i looked online and i got 1.8 kg*m/s but im not sure if its right..