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3 years ago

We can see our face clearly on mirror why cant we see our face clear on aluminium or irion plate

Physics

1 answer:

Alexxandr [17]3 years ago

3 0

Explanation:

this is due to the roughness of the metal like you mentioned aluminum and iron are rough and don't provide a reflective surface as good as a mirror

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A turntable, with a mass of 1.5 kg and diameter of 20 cm, rotates at 70 rpm on frictionless bearings. Two 540 g blocks fall from

ivann1987 [24]

Answer:

The turntable's angular speed after the event is 28.687 revolutions per minute.

Explanation:

The system formed by the turntable and the two block are not under the effect of any external force, so we can apply the Principle of Conservation of Angular Momentum, which states that:

$I_{T}\cdot \omega_{o} = (2\cdot r^{2}\cdot m +I_{T})\cdot \omega_{f}$ (1)

Where:

$I_{T}$ - Moment of inertia of the turntable, in kilogram-square meters.

$r$ - Distance of the block regarding the center of the turntable, in meters.

$m$ - Mass of the object, in kilograms.

$\omega_{o}$ - Initial angular speed of the turntable, in radians per second.

$\omega_{f}$ - Final angular speed of the turntable-objects system, in radians per second.

In addition, the momentum of inertia of the turntable is determined by following formula:

$I_{T} = \frac{1}{2}\cdot M\cdot r^{2}$ (2)

Where $M$ is the mass of the turntable, in kilograms.

If we know that $\omega_{o} \approx 7.330\,\frac{rad}{s}$ , $M = 1.5\,kg$ , $m = 0.54\,kg$ and $r = 0.1\,m$ , then the angular speed of the turntable after the event is:

$I_{T} = \frac{1}{2}\cdot M\cdot r^{2}$

$I_{T} = 7.5\times 10^{-3}\,kg\cdot m^{2}$

$I_{T}\cdot \omega_{o} = (2\cdot r^{2}\cdot m +I_{T})\cdot \omega_{f}$

$\omega_{f} = \frac{I_{T}\cdot \omega_{o}}{2\cdot r^{2}\cdot m +I_{T}}$

$\omega_{T} = 3.004\,\frac{rad}{s}$ ( $28.687\,\frac{rev}{min}$ )

The turntable's angular speed after the event is 28.687 revolutions per minute.

3 0

2 years ago

Firecracker A is 300 m from you. Firecracker B is 600 m from you in the same direction. You see both explode at the same time. D

ss7ja [257]

Answer:

e see that the distances are different, the only way that the two beams of light approach simultaneously is that event 2 (farthest) occurs first than event 1

Explanation:

This is an ejercise in special relativity, where the speed of light is constant.

Let's carefully analyze the approach, we see the two events at the same time.

The closest event time is

c = (x₁-300) / t

t = (x₁-300) / c

The time for the other event is

t = (x₂- 600) / c

since they tell us that we see the events simultaneously, we can equalize

(x₁ -300) / c = (x₂ -600) / c

x₁ = x₂ - 300

We see that the distances are different, the only way that the two beams of light approach simultaneously is that event 2 (farthest) occurs first than event 1

3 0

2 years ago

20 POINTS

Olegator [25]

Answer:

I believe the answer is B.

Explanation:

Newton's First Law of Gravity states, "The greater the weight (or mass) of an object, the more inertia it has. Heavy objects are harder to move than light ones because they have more inertia. "

6 0

3 years ago

Read 2 more answers

What is the mass of an object that creates 33750 J of energy by traveling at 30 m/s

OleMash [197]

Answer: Mass of the object is 75 kg.

4 0

2 years ago

Read 2 more answers

Which SI unit is the correctly abbreviated for describing the mass on an object.

djverab [1.8K]

S.I. Unit of mass is Kilogram which is denoted by Kg

In short, Your Answer would be Option C

Hope this helps!

4 0

3 years ago