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anonymous
 4 years ago
An electron, starting from rest and moving with a constant acceleration, travels 2.0 cm in 5.0 ms. What is the magnitude of this acceleration?
anonymous
 4 years ago
An electron, starting from rest and moving with a constant acceleration, travels 2.0 cm in 5.0 ms. What is the magnitude of this acceleration?

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JamesJ
 4 years ago
Best ResponseYou've already chosen the best response.2What's the equation of motion for a body under constant acceleration?

JamesJ
 4 years ago
Best ResponseYou've already chosen the best response.2Suppose v = initial velocity t = time a = constant acceleration Then what is the formula for the distance, d, the object moves in time t? d = ... what?

Kainui
 4 years ago
Best ResponseYou've already chosen the best response.0What is the definition of acceleration? It's the change of velocity with respect to time. How would you put this in the form of an equation?

JamesJ
 4 years ago
Best ResponseYou've already chosen the best response.2I'm going to change notation slightly, writing now u for initial velocity. Then we have: u = initial velocity t = time a = constant acceleration Write also v(t) = velocity of object at time t d(t) = position of object at time t Now, by definition, acceleration = (change in velocity)/(Time) hence \[ a = \frac{v(t)  u}{t} \] thus \[ v(t)  u = at \] and \[ v(t) = u + at \] Making sense so far?

JamesJ
 4 years ago
Best ResponseYou've already chosen the best response.2yes, what's the formula for it?

JamesJ
 4 years ago
Best ResponseYou've already chosen the best response.2Yes \[ d(t) = ut + \frac{1}{2}at^2 \] For your problem, you're told that the initial velocity is zero, t = 0.5 ms and d(0.5 ms) = 0.92 m Now calculate a.

JamesJ
 4 years ago
Best ResponseYou've already chosen the best response.2*correction, d(0.5 ms) = 0.02 m, not 0.92.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0would I try and get a by its self?

JamesJ
 4 years ago
Best ResponseYou've already chosen the best response.2Thus u = 0 m/s t = 0.005 s d = 0.02 m Substitute that into the equation above and solve for a

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0.02 = 0(.005) + .5(a)(.005)^2?

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0So if a=(v(t)−u)/t, that would equal v(t)/t, correct?

JamesJ
 4 years ago
Best ResponseYou've already chosen the best response.2but here velocity is not constant so you have to be very careful with that formula

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0But the velocity equation is dependent on the acceleration equation: v(t)=u+at

JamesJ
 4 years ago
Best ResponseYou've already chosen the best response.2Yes, so here because acceleration is constant, we're good. I.e., the average acceleration is equal to the constant acceleration.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0But the closest we got to solving for a is: .02 = 0(.005) + .5(a)(.005)^2 and v(t) needs a, v(t)=u+at I'm not getting this part, how do we solve for either one?

JamesJ
 4 years ago
Best ResponseYou've already chosen the best response.2The question only asks you to find the acceleration. Hence you only need one equation and the one that is germane herebecause it uses the information of the problemis the the one into which you've already substituted.

JamesJ
 4 years ago
Best ResponseYou've already chosen the best response.2Hence you have: .02 = 0(.005) + .5(a)(.005)^2 This already simplifies to \[ \frac{0.005^2}{2}a = 0.02 \] Now solve for \( a \).

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0A = .02(2/.005^2) = .04/.005^2?

JamesJ
 4 years ago
Best ResponseYou've already chosen the best response.2Evaluate it. You can't leave the answer in that form.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0What about the units though, is that in meters?

JamesJ
 4 years ago
Best ResponseYou've already chosen the best response.2We were (or at least I was) careful to convert all the units into SI units before we started calculating time = seconds distance = meters velocity = meters/sec = m/s acceleration = m/s^2

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0Ah, so its 1.6 km/s^2?

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0Awesome! Thanks for all your help!
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