An airliner lands with a speed of 47.0 m/s. each wheel of the
plane has a radius of1.25 m and a moment of inertia of
110kgm2.
attouchdown the wheels begin to spin under the action of
friction. each wheel supports a weight of 1.40 104
n, and the wheels attain their angular speed in 0.47 s while rolling
without slipping. what is thecoefficient of kinetic friction
between the wheels and the runway? assume that the speed of the
plane is constant.

coefficient of kinetic friction= 0.502

Explanation:

Given Data

Speed 47.0 m/s

radius=1.25 m

moment of inertia=110 kg×m²

weight=1.40×10⁴N

time=0.47 s

To find

The Coefficient of Kinetic Friction

Solution

First to find initial angular speed in radian per second

angular speed w₀ = 47 / 1.25 = 37.6 rad /sas w₀=speed/radius  

v= u+at

we have to find angular acceleration

as v=0 so

0 = 37.6 + 0.47a

a = -80 rad /s² shows it moves in anti clock wise direction

torque = Moment of Inertia * angular acceleration

t= 110 * 80

t= 8800 Nm

Now for friction force

friction force=t/radius

f f = 8800 / 1.25

f f= 7040 N

And finally to find coefficient of kinetic friction between the wheels and the runway

coefficient of kinetic friction=friction force/weight

coefficient of kinetic friction= 7040 / 1.4×10⁴

coefficient of kinetic friction= 0.502

emily ruth's annual premium is $1058.50

step-by-step explanation:

emily ruth is a female of 27 years age purchasing 20 year endowment insurance with face value $25000.

from the given table,

for females, the age of a male 3 years younger should be used.

so, we have to check for 24 year male for 20 year endowment.

it is 42.34 for every $1000 face value.

for a face value of $25000,

it is 25 * 42.34 = $1058.50

∴ emily ruth's annual premium is $1058.50

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.