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Phys 101 help



 
 
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  #1  
Old January 15th 04, 07:17 PM
phanman
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Default Phys 101 help

5. Superman jumps in front of a speeding bus, puts out his arms and
stops the bus in 1 second. If the bus was traveling at 37 mph and
weighs 57000 Lb. What force did Superman apply to the bus?
Hints:
Use the "Impulse Equation" to relate the average force to the change
in momentum in a period of time.
For the mass of the bus you use W = m · g which gives m = W / g .

Superman applied a force of__________ Lb. (Note English units.)




10. Often in movies you see a person hit by a bullet being thrown
backward by the impact of the bullet. If a 69 kg person is hit by a
51 g bullet traveling at 390 m/s what would be the velocity of the
person after the bullet hits. Assume the bullet remains in the
person.
The velocity of the person+bullet is ____________ m/s.


Thanks alot for any help



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  #2  
Old January 15th 04, 07:22 PM
John Zinni
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"phanman" wrote in message
...
5. Superman jumps in front of a speeding bus, puts out his arms and
stops the bus in 1 second. If the bus was traveling at 37 mph and
weighs 57000 Lb. What force did Superman apply to the bus?
Hints:
Use the "Impulse Equation" to relate the average force to the change
in momentum in a period of time.
For the mass of the bus you use W = m · g which gives m = W / g .

Superman applied a force of__________ Lb. (Note English units.)




10. Often in movies you see a person hit by a bullet being thrown
backward by the impact of the bullet. If a 69 kg person is hit by a
51 g bullet traveling at 390 m/s what would be the velocity of the
person after the bullet hits. Assume the bullet remains in the
person.
The velocity of the person+bullet is ____________ m/s.


Do your own homework.


  #3  
Old January 16th 04, 03:34 AM
Edward Smith
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Default

I'm not above a few hints:

5. Superman jumps in front of a speeding bus, puts out his arms and
stops the bus in 1 second. If the bus was traveling at 37 mph and
weighs 57000 Lb. What force did Superman apply to the bus?
Hints:
Use the "Impulse Equation" to relate the average force to the change
in momentum in a period of time.
For the mass of the bus you use W = m · g which gives m = W / g .

Superman applied a force of__________ Lb. (Note English units.)


Use F=ma. You can figure out the acceleration. Two things to be
careful of. Watch the gravity term and make sure your units are
consistant.





10. Often in movies you see a person hit by a bullet being thrown
backward by the impact of the bullet. If a 69 kg person is hit by a
51 g bullet traveling at 390 m/s what would be the velocity of the
person after the bullet hits. Assume the bullet remains in the
person.
The velocity of the person+bullet is ____________ m/s.


Thanks alot for any help


You could use F=ma again, but I'd use conservation of momentum.
Again, watch your units.
  #4  
Old January 16th 04, 05:42 PM
W K
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Default


"Edward Smith" wrote in message
...
I'm not above a few hints:

5. Superman jumps in front of a speeding bus, puts out his arms and
stops the bus in 1 second. If the bus was traveling at 37 mph and
weighs 57000 Lb. What force did Superman apply to the bus?
Hints:
Use the "Impulse Equation" to relate the average force to the change
in momentum in a period of time.
For the mass of the bus you use W = m · g which gives m = W / g .

Superman applied a force of__________ Lb. (Note English units.)


You know, in England - physicists use sensible units these days.

Use F=ma. You can figure out the acceleration. Two things to be
careful of. Watch the gravity term and make sure your units are
consistant.


The bus is going at about 16 m/s and the bus is about 20,000 kg.
a is 16 m/s in a second. So, thats 320,000N


  #5  
Old January 17th 04, 12:30 AM
Edward Smith
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"Edward Smith" wrote in message
.. .
I'm not above a few hints:

5. Superman jumps in front of a speeding bus, puts out his arms and
stops the bus in 1 second. If the bus was traveling at 37 mph and
weighs 57000 Lb. What force did Superman apply to the bus?
Hints:
Use the "Impulse Equation" to relate the average force to the change
in momentum in a period of time.
For the mass of the bus you use W = m · g which gives m = W / g .

Superman applied a force of__________ Lb. (Note English units.)


You know, in England - physicists use sensible units these days.

Use F=ma. You can figure out the acceleration. Two things to be
careful of. Watch the gravity term and make sure your units are
consistant.


The bus is going at about 16 m/s and the bus is about 20,000 kg.
a is 16 m/s in a second. So, thats 320,000N


I got through some college classes this way. Step 1: Convert to
Metric. Step 2: Solve Problem. Step 3: Convert back.

MUCH easier.
  #6  
Old January 17th 04, 07:43 PM
W K
external usenet poster
 
Posts: n/a
Default


"Edward Smith" wrote in message
...

"Edward Smith" wrote in message
.. .
I'm not above a few hints:

5. Superman jumps in front of a speeding bus, puts out his arms and
stops the bus in 1 second. If the bus was traveling at 37 mph and
weighs 57000 Lb. What force did Superman apply to the bus?
Hints:
Use the "Impulse Equation" to relate the average force to the change
in momentum in a period of time.
For the mass of the bus you use W = m · g which gives m = W / g .

Superman applied a force of__________ Lb. (Note English units.)


You know, in England - physicists use sensible units these days.

Use F=ma. You can figure out the acceleration. Two things to be
careful of. Watch the gravity term and make sure your units are
consistant.


The bus is going at about 16 m/s and the bus is about 20,000 kg.
a is 16 m/s in a second. So, thats 320,000N


I got through some college classes this way. Step 1: Convert to
Metric. Step 2: Solve Problem. Step 3: Convert back.

MUCH easier.


hopefully you don't do calcs for mars landers like that.


 




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