tolong dong bantuannya plis

NO. 9
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Diket :
Pers. Posisi, r = 5t⁵ + 4t⁴ - 3
waktu, t = 12 menit = 12 x 60 detik = 720 detik

Tanya :
Percpatan, a = __?

Jawab :
Step 1
---------
Cari dulu Kecepatan, 
v = dr/dt
v = d(5t⁵ + 4t⁴ - 3)/dt
v = 25t⁴ + 16t³

Step 2
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Percepatan, 
a = dv/dt
a = d(25t⁴ + 16t³)/dt
a = 100t³ + 48t²

maka saat t = 720 sec besar percpatannya adalah

a(720) = 100.(720)³ + 48.(720)²
a(720) = 100.(373248000) + 48.(518400)
a(720) = 100.(3,73248 x 10⁸) + 48.(5,184 x 10⁵)
a(720) = (3,73248 x 10¹⁰) + (2,48832 x 10⁷)
a(720) = (3732,48 x 10⁷) + (2,48832 x 10⁷)
a(720) = 3734,96832 x 10⁷ m/s²
a(720) = 3,73496832 x 10¹⁰ m/s²


No. 10
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Diket :
Pers. Percepatan, a = t + t² - t³
saat awal, t = 0 → ro = 3 m

Tanya :
saat t = 10 sec, Posisi, r = __?

Jawab :

Step 1
---------
V = ∫.a.dt
V = ∫ (t + t² - t³). dt
V = 1/2.t² + 1/3.t³ - 1/4.t⁴

Step 2
---------
Jarak posisi,
r = ro + ∫ V .dt
r = 3 + ∫ (1/2.t² + 1/3.t³ - 1/4.t⁴) .dt
r = 3 + 1/6.t³ + 1/12.t⁴ - 1/20.t⁵

maka saat t = 10 sec adalah 

r = 3 + 1/6.t³ + 1/12.t⁴ - 1/20.t⁵
r = 3 + 1/6.(10)³ + 1/12.(10)⁴ - 1/20.(10)⁵
r = 3 + 1000/6 + 10000/12 + 100000/20
r = 3 + 166,67 + 833,34 + 5000
r = 6003,01 meter

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FZA