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aquamarine08
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[SOLVED] Another work-energy theorem problem...
An automobile traveling at 45 km/h is brought to a stop in 60 m. Assuming that the same conditions (same braking force, neglect reaction time) hold for all cases, (a) what would be the stopping distance for an initial speed of 90 km/h? (b) What would be the initial speed for a stopping distance of 100 m?
w=[tex]\Delta[/tex]K
K= [tex]\frac{1}{2}[/tex]m[tex]v^{2}[/tex]
w=Fd
For (a):
Using the equation w=[tex]\Delta[/tex]K, I was substituting Fd in for w and [tex]\frac{1}{2}[/tex]m[tex]v^{2}[/tex] , making the equation Fd= [tex]\Delta[/tex][tex]\frac{1}{2}[/tex]m[tex]v^{2}[/tex]. I was going to plug in the given information and then solve for d...but I came across a problem because I don't know what the mass is and I don't know how to use [tex]\Delta[/tex] while solving either.
For (b):
I was going to use the same method to solve for v in the equation Fd= [tex]\Delta[/tex][tex]\frac{1}{2}[/tex]m[tex]v^{2}[/tex] but I encountered the same problems as before.
Thank you for your help.
Homework Statement
An automobile traveling at 45 km/h is brought to a stop in 60 m. Assuming that the same conditions (same braking force, neglect reaction time) hold for all cases, (a) what would be the stopping distance for an initial speed of 90 km/h? (b) What would be the initial speed for a stopping distance of 100 m?
Homework Equations
w=[tex]\Delta[/tex]K
K= [tex]\frac{1}{2}[/tex]m[tex]v^{2}[/tex]
w=Fd
The Attempt at a Solution
For (a):
Using the equation w=[tex]\Delta[/tex]K, I was substituting Fd in for w and [tex]\frac{1}{2}[/tex]m[tex]v^{2}[/tex] , making the equation Fd= [tex]\Delta[/tex][tex]\frac{1}{2}[/tex]m[tex]v^{2}[/tex]. I was going to plug in the given information and then solve for d...but I came across a problem because I don't know what the mass is and I don't know how to use [tex]\Delta[/tex] while solving either.
For (b):
I was going to use the same method to solve for v in the equation Fd= [tex]\Delta[/tex][tex]\frac{1}{2}[/tex]m[tex]v^{2}[/tex] but I encountered the same problems as before.
Thank you for your help.
Last edited: