Answer:
The angular speed after 6s is 
.
Explanation:
The equation
relates the moment of inertia 
of a rigid body, and its angular acceleration 
, with the force applied 
at a distance 
from the axis of rotation.
In our case, the force applied is 
, at a distance 
, to a ring with the moment of inertia of 
; therefore, the angular acceleration is
Therefore, the angular speed 
which is
after 6 seconds is
E = mgh
= (2)(9.8)(4)
= 78.4 Joules
Recall that
where 
and 
are the initial and final velocities, respecitvely; 
is the acceleration; and 
is the change in position.
So we have
(Normally, this equation has two solutions, but we omit the negative one because the car is moving in one direction.)
Answer:
The least efficient light bulb is the first one (25 W - 210 Lumen)
Explanation:
Efficiency can be defined as what you want to obtain over what you need to produce it. In this case Eff= Wattage / Lumen. For each light bulb, their efficiency is: 8.4 / 11.12 / 15.7 Lum/W
