HELP, 2 AP physics 1994 problems. Magnetic fields

[skyline_2k7]

ok guys so i have two questions, i need help on two questions on the following site "[URL


/AP%20Physics%20Daily%20Problems/AP%20Daily%20Prob%20131-140.pdf"]http://staff.hartdistrict.org/glyle/ap_physics/Homework /AP%20Physics%20Daily%20Problems/AP%20Daily%20Prob%20131-140.pdf[/URL]

they are questions #133 and 138.

please show me how to get the answers, because my head is hurting from trying to solve these questions.


thanks

 

[skyline_2k7]

ok i just found out that the link doesn't work, so i did a print screen of the pictures of the problems.

if you guys could answer these two i would appreciate it very much.

thanks

 

[Lambduh]

Read the forums rules. Make an attempt at the problem then people will be more than willing to help you :)

 

[Redbelly98]

skyline, welcome to PF.

If it helps, here are the forum rules Lambduh is referring to:

Homework Help:

On posting questions:
NOTE: You MUST show that you have attempted to answer your question in order to receive help. You MUST make use of the homework template, which automatically appears when a new topic is created in the homework help forums.

On helping with questions:
Any and all assistance given to homework assignments or textbook style exercises should be given only after the questioner has shown some effort in solving the problem. If no attempt is made then the questioner should be asked to provide one before any assistance is given. Under no circumstances should complete solutions be provided to a questioner, whether or not an attempt has been made.

(From https://www.physicsforums.com/showthread.php?t=5374 )

So if you can think about it and tell us something you know about solving the problems, we can offer hints and steer you in the right direction.

 

[skyline_2k7]

ok so

a)im pretty sure that potential difference is the voltage, but i don't know of an equation that has the variables a and V in them. so I am stuck there.

b) i think that you might need to set 1/2 m v^2 equal to something else but i don't know that equation either, but you do know the mass of a proton and the velocity is given to you.

c)i think that this is the equation r= mv/qb and just plug everything in and solve for B.

d) I am pretty sure its negative Z, into the the page because of the right hand rule.

and for the next problem i have absolutely no clue whatsoever :(

 

[Redbelly98]

Okay, let's work out the first 2 parts first.

ok so

a)im pretty sure that potential difference is the voltage, but i don't know of an equation that has the variables a and V in them. so I am stuck there.

Yes, potential difference is the voltage. And voltage (by definition) is the ratio of energy/charge.

So if you knew the kinetic energy gained by each proton, as well as the charge on each proton, you could figure out the voltage.

b) i think that you might need to set 1/2 m v^2 equal to something else but i don't know that equation either, but you do know the mass of a proton and the velocity is given to you.

That's a decent start. Since the proton beam is stopped by the target, all the kinetic energy of each proton will be converted to heat in the target. Note that heat has units of energy, so it is a direct conversion,

kinetic energy → heat energy​

See if you can get those first 2 for now ... or ask for more clarification if you can't.

Regards,

RB