A flow of electricity that constantly reverses direction. In the United States it reverses itself 120 times per second.

Physics

1 answer:

Vladimir [108]3 years ago

7 0

D an alternating current because it reverses constantly.

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List five situations in which a lesser amount of friction would be beneficial. Overall, would a high or low coefficient of frict

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Low coefficient of friction

1. flying a plane (friction between air and plane)
2. ice skating (friction between ice and skate blade)
3. swimming (water & skin)
4. rowing a boat (water and boat)

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With a diameter that's 11 times larger than Earth's, _______ is the largest planet.

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With a diameter that's 11 times larger than Earth's, Jupiter is the largest planet

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What is the evidence proving that we're in the 6th mass extinction?

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To meet a U.S. Postal Service requirement, employees' footwear must have a coefficient of static friction of 0.5 or more on a sp

motikmotik

Answer:

0.79 s

Explanation:

We have to calculate the employee acceleration, in order to know the minimum time. According to Newton's second law:

$\sum F_x:f_{max}=ma_x\\\sum F_y:N-mg=0$

The frictional force is maximum since the employee has to apply a maximum force to spend the minimum time. In y axis the employee's acceleration is zero, so the net force is zero. Recall that $f_{max}=\mu N$

Now, we find the acceleration:

$\mu N=ma_x\\\mu mg=ma_x\\a_x=\mu g\\a_x=0.83(9.8\frac{m}{s^2})\\a_x=8.134\frac{m}{s^2}$

Finally, using an uniformly accelerated motion formula, we can calculate the minimum time. The employee starts at rest, thus his initial speed is zero:

$x=v_0t+\frac{1}{2}a_xt^2\\2x=a_xt^2\\t=\sqrt{\frac{2x}{a}}\\t=\sqrt{\frac{2(3.2m)}{8.134\frac{m}{s^2}}}\\t=0.79 s$

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3 years ago

in a railyard a train is being put together from freight cars.An empty freight car coasting 10 m/s strikes a loaded car that is

svetoff [14.1K]

Answer:m1v1 + m2v2 = (m1f + m2f)vf. 3000kg(10.0m/s) + (15000kg)(0.0m/s) = (18000kg)(vf).

Explanation:

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2 years ago