Answer:
With a tape measure.
Explanation:
We can use a big tape measure, this tape is in the market and we can use the one with the proper length that lets us measure different sections of the total length of the pool.
Answer:
8 km/hr
Explanation:
Convert minutes to hours:
30 min × (1 hr / 60 min) = 0.5 hr
Average speed is distance over time:
v = (4 km) / (0.5 hr)
v = 8 km/hr
Answer:
a) = 72.75 kg
, b) V = 0.07275 m³
, c) ρ₂ = 1030.9 km / m³
, d) ρ₂= 996 kg / m³ float
Explanation:
This is an exercise that we must solve using the Archimedes principle, where the thrust is
B = ρ g V
a) Let's use Newton's second law
F = B - W
F = ρ g V - mg
The force is the apparent weight (m₂ = 2.25 kg) is directed downwards so it is negative
F = m₂ g
-m₂ g = ρ g V - m g
-m₂ g = g - mg
= -m₂ + m
= -2.25 + 75.0
= 72.75 kg
b) let's use the definition of density
ρ = m / V
V = m /ρ
V = 72.75 / 1000
V = 0.07275 m³
c) the density of man is
ρ₂ = m / V
ρ₂ = 75.0 / 0.07275
ρ₂ = 1030.9 km / m³
d) the volume of man increases because the lungs are full of air, as they are half full, with a capacity of 2.5 liters and two lungs the volume is
V’= ½ 2.5 2
V’= 2.5 liters
V’= 2.5 10⁻³ m³
The total volume of man is
Vt = 0.07275 + 0.0025
Vt = 0.07525
Let's calculate the density
ρ₂ = 75.0 / 0.07525
ρ₂= 996 kg / m³
As this is less than the density of water (1000 kg / m3) man must float
Because it is really hard and rocks can't be visible or vibrate