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podryga [215]
3 years ago
5

A DVD drive is spinning at 100.0 rpm. A dime (2.00 gm) is placed 3.00 cm from the center of the DVD. What must the coefficient o

f friction be to keep the dime on the disk?
Physics
1 answer:
seropon [69]3 years ago
8 0

Answer:

0.3375

Explanation:

w = angular speed of the DVD drive = 100.0 rpm = 100.0 \frac{rev}{min}\frac{2\pi rad}{1 rev}\frac{1 min}{60 sec} = 10.5\frac{rad}{sec}

m = mass of the dime = 2 g = 0.002 kg

r = radius = 3 cm = 0.03 m

μ = Coefficient of friction

The frictional force provides the necessary centripetal force to move in circle. hence

frictional force = centripetal force

μ mg = m r w²

μ g =  r w²

μ (9.8) =  (0.03) (10.5)²

μ = 0.3375

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A ball is whirled on the end of a string in a horizontal circle of radius R at constant speed v. Complete the following statemen
Eva8 [605]

Answer:

Keeping the speed fixed and decreasing the radius by a factor of 4

Explanation:

A ball is whirled on the end of a string in a horizontal circle of radius R at constant speed v. The centripetal acceleration is given by :

a=\dfrac{v^2}{R}

We need to find how the "centripetal acceleration of the ball can be increased by a factor of 4"

It can be done by keeping the speed fixed and decreasing the radius by a factor of 4 such that,

R' = R/4

New centripetal acceleration will be,

a'=\dfrac{v^2}{R'}

a'=\dfrac{v^2}{R/4}

a'=4\times \dfrac{v^2}{R}

a'=4\times a

So, the centripetal acceleration of the ball can be increased by a factor of 4.

7 0
3 years ago
A loud sound is produced in the downtown section of a city. Which of the following is least likely to occur with the sound wave
JulsSmile [24]

Answer:

A. The sound wave will reflect off Buildings and automobiles.

Explanation:

This is because the sound waves would more likely propagate through diffraction through buildings and transmission through the air. It is also more likely to be absorbed by buildings than for multiple reflections to occur off buildings and automobiles. In the process of reflection, these materials would absorb the sound energy thereby reducing its ability to reflect.

6 0
3 years ago
One of the dangers of tornados and hurricanes is the rapid drop in air pressure that is associated with such storms. Assume that
Rufina [12.5K]

Answer:

45930.52N

Explanation:

Net force = (internal pressure - external pressure)× area of window

Net force = (1.02 - 0.910)atm × 2.03m × 2.03m = 0.11atm × 4.1209m^2 = 0.11 × 101325N/m^2 × 4.1209m^2 = 45930.52N

5 0
3 years ago
A cat runs and jumps from one roof top to another which is 5 m away and 3 m below. Calculate the minimum horizontal speed with w
icang [17]
ThIs is the same type of problem
find out the time value
3 = 1/2*a*T^2
6/10 = t^2
t = 0.77 seconds
and the distance is given 5 m
thus speed ,= distance/time
speed = 5/0.77
= 6.45 m/s
6 0
3 years ago
What contributions did J.J. Thomson make to atomic history?
luda_lava [24]
J.J. Thomson discovered electrons and noticed that an atom can be divided. Also, he concluded atoms are made of positive cores and negatively charged particles within it.
4 0
3 years ago
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