Answer:
4.61 seconds
Explanation:
Given data
Initial velocity= 12m/s
acceleration= -2.6m/s^2
From the given data
we can find the time t
we know that
Acceleration= velocity/time
time= velocity/acceleration
time= 12/2.6
time= 4.61 seconds
The preamble rock is filled with air spaces
A material that does not conduct electricity is known as an insulator
Answer: B
It can exist in many alloys, usually with a carbon base
Explanation:
Iron forms many alloys with a carbon base. Steel is an alloy of iron and carbon. There are many different types of steel needed for different applications. Various metals are added to tune the steel to the required properties. For instance, stainless steel contains 10-30% chromium in addition to iron and a low percentage of carbon. Steel remains an extremely versatile alloy used for many different purposes.
Answer:
a. 16 s b. -1.866 kJ
Explanation:
a. Since the initial rotational speed ω₀= 3313 rev/min = 3313/60 × 2π rad/s = 346.94 rad/s. Its rotational speed becomes ω₁ = 0.75ω₀ in time t = 4 s.
We find it rotational acceleration using α = (ω₁ - ω₀)/t = (0.75ω₀ - ω₀)/t = ω₀(0.75 - 1)/t = -0.25ω₀/t = (-0.25 × 346.94 rad/s)/4 s = -21.68 rad/s².
Since the turntable stops at ω = 0, the time it takes to stop is gotten from
ω = ω₀ + αt and t = (ω - ω₀)/α = (0 - 346.94 rad/s)/-21.68 rad/s² = (-346.94/-21.68) s = 16 s.
So it takes the turntable 16 s to stop.
b. The workdone by the turntable to stop W equals its rotational kinetic energy change.
So, W = 1/2Iω² - 1/2Iω₀² = 1/2 × 0.031 kgm² × 0² - 1/2 × 0.031 kgm² × (346.94 rad/s)² = 0 - 1865.7 J = -1865.7 J = -1.8657 kJ ≅ -1.866 kJ
