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Physics

1 answer:

natima [27]3 years ago

8 0

Answer:

25000W

Explanation:

Kinetic Energy, EK=(1/2)mv2. Energy is conserved, so the work done by the brakes, W, must be equal to the change in kinetic energy of the car, ∆EK. Therefore: W = ∆EK = (1/2)1000(152-52) = 0.51000200 = 100000 = 1*105J. Since power P = W/T, the average power output of the brakes is equal to the total work done by the brakes over the time that the brakes are applied for, therefore: P = 100000/4 = 25000W.

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How can athletes promote social<br> justice?

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ORLANDO, Fla. —

The NBA playoffs will pick up again this weekend after players made a powerful statement on Wednesday.

Athletes have a voice when it comes to change and demands for social justice. Their impact is extending off the court and into the world.

"We stand with them, we support them and we're there for them," Michael-Carter Williams said.

The Orlando Magic's Michael Carter-Williams spoke Thursday about the Milwaukee Bucks' decision not to play Wednesday and instead, making a demand for the end to social injustice.

"We have a big platform that we can use to really make change in this country and we can go home to our communities and make change there," Carter-Williams said.

The Bucks' decision led to all NBA games being postponed Wednesday, some baseball games weren't played, as well as soccer, and the WNBA.

"This was a historic moment last night, we never had anything like that happen before," Dr. Richard Lapchick said.

Lapchick is a UCF professor who is also the president of the Institute for Sport and Social Justice.

He says the impact from Wednesday's boycott can't be overstated.

"The unity that occurred between the players and teams and leagues, was particularly impressive," Lapchick said. "The importance of what the players are doing, and what the country is doing in response, is looking at more than police brutality, it's looking at systemic racism."

"People are just tired of what's going on, there's no justice at all," Sandy Lallavee said.

Lallavee is one of the many residents we spoke to who supports the athletes' desire for a committed dialogue and effective change.

"I think it's the right thing to do right now, I support their decision and I think it's terrible what's happening in the world, in America," Gerrod Trytten said.

"It's a younger generation doing things and trying to make change, I respect them and I think they're doing the right thing," Nick Trapp said.

"They're showing their humanity, they're showing what they really care about in society," Lapchick said.

6 0

3 years ago

If the current in a wire increases from 5 A to 10 A, what happens to its magnetic field? If the distance of a charged particle f

dsp73

1. The magnitude of the magnetic field doubles

Explanation: the intensity of the magnetic field produced by a current-carrying wire is given by:

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

where $\mu_0$ is the vacuum permeability, I is the current in the wire, r is the distance from the wire.

As we see from the formula, the intensity of the magnetic field is directly proportional to the current: if the current increases from 5 A to 10 A, it means it doubles, so the magnetic field doubles as well.

2. The magnitude of the magnetic field halves

Explanation: the intensity of the magnetic field produced by a current-carrying wire is given by:

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

We see that the magnitude of the magnetic field is inversely proportional to the distance from the wire (r). In this case, the distance of the particle is changed from 10 cm to 20 cm, so it is doubled: therefore, the magnitude of the field will become half of the initial value.

3. The force reverses direction

Explanation: the force exerted on a charged particle in a magnetic field is:

$F=qvB sin \theta$

where q is the charge, v is the speed of the particle, B is the magnetic field intensity and $\theta$ the angle between the direction of v and B. If the charge of the particle is switched from 2 µC to –2µC, the magnitude of the force does not change (because the absolute value of q does not change), however the charge q gets a negative sign (-), so the sign of the force changes and gets a negative sign too, so the force reverses direction.