Answer:
Moment of inertia of the system is 289.088 kg.m^2
Explanation:
Given:
Mass of the platform which is a uniform disk = 129 kg
Radius of the disk rotating about vertical axis = 1.61 m
Mass of the person standing on platform = 65.7 kg
Distance from the center of platform = 1.07 m
Mass of the dog on the platform = 27.3 kg
Distance from center of platform = 1.31 m
We have to calculate the moment of inertia.
Formula:
MOI of disk = 
Moment of inertia of the person and the dog will be mr^2.
Where m and r are different for both the bodies.
So,
Moment of inertia 
of the system with respect to the axis yy.
⇒ 
⇒ 
⇒ 
⇒ 
The moment of inertia of the system is 289.088 kg.m^2
For an inelastic collision where coefficient of restitution,e, is equal to 0, the momentum is conserved but not the kinetic energy. So, there is addition or elimination of kinetic energy.
On the otherhand, when e = 1, like for an elastic collision, kinetic energy and momentum is conserved. Thus, the system's kinetic energy is unchanged.
Answer:
The force is 274 N.
Explanation:
In figure 2:
(d) Let the tension in the string is T.
According to the Newton's second law,
Net force = mass x acceleration
Apply for 200N.
Now put in (1)
T - 114.7 = 20.4 x 7.81
T = 274 N
Answer:
Before giving an injection, a nurse dabs some alcohol onto the patient`s arm. This makes the patient`s skin feels cold. Explain Why ?
<em> Evaporative cooling makes this to be possible</em>
Explanation:
The concept
For a liquid to evaporate, there must be a breakdown of the bond between the molecules of the liquid. These bonds are broken when the molecules gain heat energy. So basically evaporation occurs when the molecules of the substance gain energy in form of heat.
Our Scenario
Just like the way our body excretes sweat on a sunny day, alcohol takes energy from the skin to evaporate. The bond holding the molecules of alcohol breaks faster due to its low boiling point and this account why it evaporates faster. The sudden evaporation of alcohol when dabbed on the skin results in quick utilization of heat energy making the skin feel cold for some time.
The utilization of heat energy from the skin results in evaporation cooling which makes the skin feel colder.
