Jawaban:

1.

Kerikil

m = 1000 g = 1 kg

v = 750-300 = 450 cc = 0,00045 m³

ρ = ?

RD = ?

ρ = m/v = 1/0,00045 = 2222,22 kg/m³

RD = ρ/ρₐᵢᵣ  (massa jenis relatif)

RD = 2222,22/1000 = 2,222 kg/m³  

2.

m₁ = 200kg

A₁ = ?

m₂ = 70kg

d₂ = 10 cm = 0,1 m

r = d/2 = 0,05 m

A₂ = πr² = π0,05² = 0,0025π  m²

F₂ = mg = 70g  (gaya berat)

F₁ = m₁g = 200g

A₁ = πr²

Hukum Pascal

P₁ = P₂

F₁/A₁ = F₂/A₂

200g/πr² = 70g/0,0025π

200/r² = 70/0,0025

0,5 = 70r²

r² = 0,00714 m

r = 0,0845 m

d =2r = 0,169 m = 16,9 cm

3.

lo = 7m

d = 0,5 cm = 0,005 m

r = d/2 = 0.0025m

E = 5x10⁹ N/m²

F = 400 N

Δl = ?

A = πr² = 3,14x0.0025² = 0,0000196 m²

E = F lo / Δl A

5x10⁹ = 400 x 7/Δlx0,0000196

Δl = 2800/98000 = 0,02857 m

Penjelasan: