another problem :(

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Kenneth Bryan M...
Kenneth Bryan Mendoza Rimocal's picture
another problem :(

a car if nass 1600kg coast down a 10 percent grade from A to B, a distance of 30m and then coast along a level road until it stops at C. assume the road resistance to remain constant of 200N for the entire distance A to C, if the initial velocity of the car at A is 25kph, compute:

a.) its velocity at B
b.) the distance s it coast from B to C.

Jhun Vert
Jhun Vert's picture

Motion from A to B

EA - Friction Work = EB
$\left[ \frac{1}{2}(1600)\left( \dfrac{25}{3.6} \right)^2 + 1600(9.81) \left( \dfrac{30}{\sqrt{101}} \right) \right] - 200(30) = E_B$

$E_B = 79,434.56 ~ \text{N}\cdot\text{m}$

$\frac{1}{2}(1600)\left( \dfrac{v_B}{3.6} \right)^2 = 79,434.56$

$v_B = 35.87 ~ \text{kph}$

 

win_20150421_094416.jpg

 

Motion from B to C

EB - Friction Work = EC
$79,434.56 - 200s_{BC} = 0$

$s_{BC} = 397.17 ~ \text{m}$

 
 
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