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Dahasolnce [82]
3 years ago
12

Consider an eraser, weighing 20g, sitting 5cm from the center of a turntable (flat disk attached to a motor which can spin the d

isk up or down). If the coefficient of static friction between the eraser and the turntable is 0.1, and the turntable is slowly spun-up just shy of the spin rate at which the eraser starts to slip
A.Calculate how many revolutions the turntable will make every minute at the end (when the eraser is just about to slip). Show your reasoning!
B.What force is responsible for making the eraser go faster while the turntable is spinning up?
Physics
1 answer:
Artist 52 [7]3 years ago
7 0

Answer:

A. 42.3 revolution per minute

B. Centripetal Force

Explanation:

20 g = 0.02 kg

5 cm = 0.05 m

Let g = 9.8 m/s2

A.The friction force acting on the eraser is the product of normal force and its coefficient:

F_f = N\mu = mg\mu = 0.02*9.8*0.1 = 0.0196 N

For the eraser to begin slipping, its centripetal acceleration must win over the acceleration created by friction force, which is

a_f = F_f / m = 0.0196 / 0.02 = 0.98 m/s^2 = a_c

We can calculate the angular velocity from this:

a_c = \omega^2 r

where r = 0.05 is the radius of rotation, which is distance from the center to the eraser

\omega^2 = a_c/r = 0.98 / 0.05 = 19.6

\omega = \sqrt{19.6} = 4.43 rad/s

If it spins and angle of 4.43 rad per second then for every minute (60 seconds) it would spin an angle of 4.43 * 60 = 265.6 rad/min

Since 1 revolution is 2π rad, then in a minute it would spin 265.6 / 2π = 42.3 revolution/minute

B. The force responsible for making the eraser go faster while the turntable is spinning up would be the centripetal force.

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skad [1K]

Answer:

2,100J

Explanation:

Workdone=Force x distance

=700 x 3

=2,100 J

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3 years ago
If you push on the wall with a force of 400 N, what is the magnitude of the force at the wall exerts on you?
Inessa05 [86]

Answer:

400 N

Explanation:

Due to action-Reaction, the wall pushes back on the person with a force of equal magnitude and in opposite direction to the force exerted by the person.

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The heat flux for a given wall is in the x-direction and given as q^n = 11 W/m^2, the walls thermal conductivity is 1.7 W/mK and
MrMuchimi

Answer:

\frac{dT}{dx} = 6.47 ^oC/m

Also as we can see the equation that heat flux directly depends on the temperature gradient so more is the temperature gradient then more will be the heat flux.

For positive temperature gradient the heat will flow outwards while for negative temperature gradient the heat will flow inwards

Explanation:

As we know that heat flux is given by the formula

q^n = K\frac{dT}{dx}

here we know that

K = thermal conductivity

\frac{dT}{dx} = temperature gradient

now we know that

q^n = 11 W/m^2

also we know that

K = 1.7 W/mK

now we have

11 = 1.7 \frac{dT}{dx}

so temperature gradient is given as

\frac{dT}{dx} = \frac{11}{1.7} = 6.47 K/m

also in other unit it will be same

\frac{dT}{dx} = 6.47 ^oC/m

Also as we can see the equation that heat flux directly depends on the temperature gradient so more is the temperature gradient then more will be the heat flux.

For positive temperature gradient the heat will flow outwards while for negative temperature gradient the heat will flow inwards

5 0
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A car's gas tank contains 58.7 kg
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Answer:

721 kg/m^3

Explanation:

Trust me bro

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A 1.0 kg object is attached to a string 0.50 m. It is twirled in a horizontal circle above the ground at a speed of 5.0 m/s.
zysi [14]

Answer: d

Explanation:

For an object to move in a uniform circular motion, only force that acts on it is the centripetal force which acts along the line joining the object and center of the circular path. The acceleration also acts in the direction of force. The centripetal acceleration acts along the radius of the circular motion path.

In the given horizontal circle, the direction of the acceleration of the object points towards d.

6 0
3 years ago
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