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3 years ago

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A cart starts from rest and accelerates at 4.0 m/s2 for 5.0 s, then maintains that velocity for 10 s, and then decelerates at th

e rate of 2.0 m/s2 for 4.0 s. What is the final speed of the car?

1 answer:

zhannawk [14.2K]3 years ago

3 0

Answer:

Final speed of car = 12 m/s

Explanation:

We have equation of motion v = u + at, where v is final velocity, u is initial velocity, a is acceleration and t is time.

a) A cart starts from rest and accelerates at 4.0 m/s² for 5.0 s

v = ?

u = 0 m/s

a = 4.0 m/s²

t = 5 s

v = u + at = 0 + 4 x 5 = 20 m/s

b) Then maintains that velocity for 10 s

v = ?

u = 20 m/s

a = 0 m/s²

t = 10 s

v = u + at = 20 + 0 x 10 = 20 m/s

c) Then decelerates at the rate of 2.0 m/s² for 4.0 s

v = ?

u = 20 m/s

a = -2.0 m/s²

t = 4 s

v = u + at = 20 + -2 x 4 = 12 m/s

Final speed of car = 12 m/s

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Explanation:

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Also $T_f$ is mathematically represented as

$T_f = KE_f + PE_f$

Here

$PE_f$ is the final potential energy which is mathematically represented as

$PE_f = \frac{k * Q_1 * Q_2}{r}$

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So

$KE_i + PE_i = KE_f + PE_f$

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So

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=> $u = \sqrt{\frac{3.68*10^{-13} + 5.027 *10^{-13 }}{0.5 * 1.67*10^{-27}} }$

=> $u = 3.23 *10^{7} \ m/s$

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