<span>If the thermostat gets too hot, it will turn off the heat an turn on the air conditioner. If a thermostat gets too cool it will turn on the heat or turn off the cold air. The human body is similar to a thermostat because if people get cold, they get covered in goosebumps, if they get too hot they begin to sweat.</span>
Answer:
0.70 s
Explanation:
Potential energy = kinetic energy + rotational energy
mgh = ½ mv² + ½ Iω²
For a thin spherical shell, I = ⅔ mr².
mgh = ½ mv² + ½ (⅔ mr²) ω²
mgh = ½ mv² + ⅓ mr²ω²
For rolling without slipping, v = ωr.
mgh = ½ mv² + ⅓ mv²
mgh = ⅚ mv²
gh = ⅚ v²
v = √(1.2gh)
v = √(1.2 × 9.81 m/s² × 1.1 m sin 49.0°)
v = 3.13 m/s
The acceleration down the incline is constant, so given:
Δx = 1.1 m
v₀ = 0 m/s
v = 3.13 m/s
Find: t
Δx = ½ (v + v₀) t
t = 2Δx / (v + v₀)
t = 2 (1.1 m) / (3.13 m/s + 0 m/s)
t = 0.704 s
Rounding to two significant figures, it takes 0.70 seconds.
The answer is either
b A system in which Newton's Laws are valid
or
c A system in which there are no external forces.
Explanation:
not a, and not d
There are energy changes in a closed system.
A closed system obeys the conservation laws in its physical description.
Answer:
at R/
Explanation:
The free-fall acceleration at the surface of Earth is given by
where
G is the gravitational constant
M is the Earth's mass
R is the Earth's radius
The formula can be rewritten as
(1)
We want to shrink the Earth at a radius R' such that the acceleration of gravity becomes 3 times the present value, so
g' = 3g
Keeping the mass constant, M, and substituting into the equation, we have
