DINAMIKA ROTASI

▶ Momen Gaya, Energi Kinetik Rotasi

ρ = 2 g/cc = 2000 kg/m³

R = 5 cm = 5 × 10⁻² m

F = 10 N

a ]

α = __ ?

hitung massa bola pejal

m = ρ V

m = ρ (⁴/₃ π R³)

m = 2000 × ⁴/₃ × 3,14 × (5 × 10⁻²)³

m ≈ 1,046 kg

hitung momen inersia bola pejal

I = ⅖ m R²

I = ⅖ × 1,046 × (5 × 10⁻²)²

I ≈ 1,046 × 10⁻³ kg m²

hitung percepatan sudut

τ = I α

F R = I α

10 × 5 × 10⁻² = 1,046 × 10⁻³ × α

α ≈ 478 rad/s² ✔

b. ]

t = 3 s

Ek = __ ?

hitung kecepatan sudut

ωₜ = ω₀ + αt

ωₜ = 0 + 478 × 3

ωₜ ≈ 1434 rad/s

hitung Ek rotasi

Ek = ½ I ωₜ²

Ek = ½ × 1,046 × 10⁻³ × 1434²

Ek ≈ 1075,47 J ✔