This is another annoying linear momentum..pls answer wat u can answer thnx...^_^?

Question

1.) Find the momentum of a 50-g bullet whose KE is 250 J
2.) Find the momentum of a giraffe galloping at 20km/h whose KE is 6.0kJ
3.) Find the momentum of a 3200-lb car moving at 3-mi/h
4.) Find the momentum of a 0.40-lb bullet whose KE is 1600-ft x(times) lb
5.)Car A has a mass of 1000kg and is moving at 30km/h. Car B has a mass of 2000kg and is moving at 30km/h. Compare the KE and momenta of the two cars.
6.) A 1000kg car strikes a tree at 30km/h and comes to a stop in 0.15 s. Find its initial momentum and the average force on the car while it is beong stopped.
7.) A 160,000kg DC-8 airplane is flying at 870km/h.(a)Find its momentum.(b)If the thrust its engines develop 340kN, how much is needed for the airplane to reach this speed starting from rest? Neglect air resistance, changes in altitude, and fule consumed
8.)A 1/3lb baseball reaches a batter with a speed of 75ft/s. After it has been strucked, it leaves the bat at 100ft/s in op. direction. ball to bat=1.0 ms. find the ave. force

Answer 1

I suggest one question per post.

1. KE=.5*m*v^2
and momentum =m*v
you know KE and m so
(50/1000)*
sqrt(250*2*1000/50)=m*v

2. similar
convert km/hr to m/s
20*60*60/1000=v
6000=.5*m*v
solve for m since you know v

3) Similar, convert the units and muliply mass by velocity.

4. Again, convert the units

5. Car A momentum
1000*30*3.6
KE=.5*1000*(30*3.6)^2

and so on

6. The average force can be calculated by first finding the average velocity which is initial divided by two. Then the "distance" is average velocity multiplied by time. Then compute the initial kinetic energy of the car KE, and use the following equation:
KE=distance*average force

7. You know the thrust force and the final speed. Compute the final kinetic energy based on the speed alone, this is how much energy the engines must do work that is equivalent to.

8. More of the same.

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