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Gwar [14]
3 years ago
14

Which of the following best demonstrates the effect of static friction? A. A person dropping a ball to the ground. B. A person p

ushing a couch and it slowly sliding across a floor C. A person pushing a couch without being able to move it D. A person moving a ball through a stream of water
Physics
1 answer:
Dominik [7]3 years ago
6 0

Answer:

C.

Explanation:

A person pushing a couch will face resistive force of friction . When resistive force is greater then his force of effort , couch will not move. This force is static friction because the couch is stationary. When the force of effort is increased , magnitude of static friction also increases keeping the couch stationary. The ability of the static friction to increase its magnitude is limited by a maximum value beyond which the couch starts moving. The static friction is then converted into kinetic friction.

In rest of the three cases object is already moving so kinetic friction is in action.

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I am quite sure the first one is Friction, but I am not sure about the second one. Is it wind?
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Imagine you are holding an apple. a. Does this apple have energy? How do you know? b. How could you increase the potential energ
Len [333]
A).  The apple has thermal energy, because its temperature is higher
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It also has chemical energy, because if I eat it, I get a burst of energy
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3 years ago
A coaxial cable consists of a solid inner cylindrical conductor of radius 2 mm and an outer cylindrical shell of inner radius 3
4vir4ik [10]

Answer:

d) 1.2 mT

Explanation:

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First of all, we observe that:

- The internal cylindrical conductor of radius 2 mm can be treated as a conductive wire placed at the axis of the cable, since here we are analyzing the field outside the radius of the conductor. The current flowing in this conductor is

I = 15 A

- The external conductor, of radius between 3 mm and 3.5 mm, does not contribute to the field at r = 2.5 mm, since 2.5 mm is situated before the inner shell of the conductor (at 3 mm).

Therefore, the net magnetic field is just given by the internal conductor. The magnetic field produced by a wire is given by

B=\frac{\mu_0 I}{2\pi r}

where

\mu_0 is the vacuum permeability

I = 15 A is the current in the conductor

r = 2.5 mm = 0.0025 m is the distance from the axis at which we want to calculate the field

Substituting, we find:

B=\frac{(4\pi\cdot 10^{-7})(15)}{2\pi(0.0025)}=1.2\cdot 10^{-3}T = 1.2 mT

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6 0
3 years ago
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Answer:

3.14946 rad/s

Explanation:

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\omega_i = Initial angular velocity

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\dfrac{I_f}{I_i}=\dfrac{1}{3}

In this system the angular momentum is conserved

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The angular velocity when the diver left the board is 3.14946 rad/s

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3 years ago
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