Adding oil to the moving parts of machines can do that because it makes it smoother and takes the rust off of it.
Complete Question
Suppose a NASCAR race car rounds one end of the Martinsville Speedway. This end of the track is a turn with a radius of approximately 57.0 m . If the track is completely flat and the race car is traveling at a constant 30.5 m/s (about 68 mph ) around the turn.
Required:
a. What is the race car's centripetal (radial) acceleration?
b. What is the force responsible for the centripetal acceleration in this case?
O normal
O gravity
O friction
O weight
Answer:
question a

question b
correct option is option 3
Explanation:
From the question we are told that
The radius is 
The constant speed at which the race car is travelling is 
Generally from the question we are told that the track is completely flat so the only force pulling the car to the middle is the frictional force hence the centripetal force is due to the frictional force
Generally the centripetal acceleration is mathematically represented as

=> 
=> 
If the radius of the cylinder is halved and length is kept unchanged then the density of air inside the cylinder will increase.
As it can be said that density is inversely proportion to the square of the radius.
Density of Cylinder
Density is the ratio of mass to volume.
The formula for density is: ρ= m/v.
The formula for the Mean Density of a cylinder is:
ρ= m/ (π•r²•h)
where:
ρ is the density of the cylinder
m is the mass of the cylinder
h is the height of the cylinder
So, with increase in radius the of the cylinder there is decrease in the density of cylinder.
And on decreasing the radius of the cylinder there is increase in the density of the cylinder.
As it can be said that density is inversely proportion to the square of the radius.
To learn more about Density Of Cylinder
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