Calculating the corresponding percentage

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SUMMARY

The discussion focuses on calculating the percentage fall in speed of a car that initially travels at 5.5 m/s and experiences a 51% reduction in kinetic energy while descending an 8-degree incline. The kinetic energy formula, Ek = 1/2mv², is utilized to derive the relationship between the initial and final kinetic energies. By establishing that Ek is reduced to 49% of its initial value, participants are guided to find the corresponding percentage decrease in speed through the equation v² = (2 * 0.49 * Ek) / m.

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  • Understanding of kinetic energy and its formula (Ek = 1/2mv²)
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Homework Statement



A car is traveling at initial speed 5.5ms-1. The car is on a decline of 8o. The brakes are used and the car stops after traveling 10m along the road (with no skidding).

At the moment when kinetic energy is 51% lower than the initial value,
find the corresponding percentage fall in speed.


Homework Equations


Ek = 1/2mv2


The Attempt at a Solution


E is 51% lower, so \frac{2(0.49)Ek}{m}=v2
Clueless?!
 
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Start with

\frac{Ek_2}{Ek_1}=\frac{49}{100}

From that relationship, get a relationship between the two velocities.
 

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