Answer:

Explanation:
When the rock is immersed in unknown liquid the forces that act on it are shown as under
1) Tension T by the string
2) Weight W of the rock
3) Force of buoyancy due to displaced liquid B
For equilibrium we have 
=
When the rock is suspended in air for equilibrium we have

When the rock is suspended in water for equilibrium we have
+
=
Using the given values of tension and solving α,β,γ simultaneously for
we get

Solving for density of liquid we get


Answer:
Explanation:
A.
Given:
Vo = 21 m/s
Vf = 0 m/s
Using equation of Motion,
Vf^2 = Vo^2 - 2aS
S = (21^2)/2 × 9.8
= 22.5 m.
B.
Given:
S = 22.5 + 21 mm
= 22.521 m
Vo = 0 m/s
Using the equation of motion,
S = Vo × t + 1/2 × a × t^2
22.521 = 0 + 1/2 × 9.8 × t^2
t^2 = (2 × 22.521)/9.8
= 4.6
t = 2.14 s
Answer:

Explanation:
Dimensions of mattress 100 cm by 194 cm by 14 cm
= Mass of mattress = 4 kg
= Density of water = 
g = Acceleration due to gravity = 
Volume of mattress

Weight of water displaced is equal to the buoyant force
Mass of water

Mass of person would be

Weight of the person would be

The air mattress could hold a person that weighs up to
.
Answer:
a) 3.00×10⁸ m/s
b) 2.9979×10⁸ m/s
c) 2.997925×10⁸ m/s
Explanation:
299792458 m/s is the speed of light
Let us write this in scientific notation first
2.99792458×10⁸ m/s
a) In three significant figures
We need to round the number to the hundredths place
3.00×10⁸ m/s
b) In five significant figures
We need to round the number to the ten thousandths place
2.9979×10⁸ m/s
c) In seven significant figures
We need to round the number to the millionths place
2.997925×10⁸ m/s