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Sedaia [141]
3 years ago
9

A 72.0-kg object hits the ground at a velocity of 79.0 m/s. Neglecting air resistance, which relationship allows you to calculat

e the object’s potential energy before the fall? A. PE = mgh B. (PE)beginning = (KE)end C. Mechanical Energy = PE + KE D. KE = 1/2 mv2
Physics
1 answer:
kondaur [170]3 years ago
8 0
<h3>Answer:</h3>

B. (PE)beginning = (KE)end

<h3>Explanation:</h3>

<u>We are given;</u>

  • Mass of an object is 72.0 kg
  • Velocity of the body before it hits the ground is 79.0 m/s

We are required to determine the relationship between the potential energy and kinetic energy before the fall.

  • When an object is at the highest point, it has maximum potential energy and minimum kinetic energy.
  • This is because potential energy is directly proportional to the height of an object above the earth's surface.
  • On the other hand, when an object attains the highest speed it has maximum kinetic energy and minimum kinetic energy.

In this case;

  • The velocity of the object when hitting the ground is maximum and thus the object will have maxim,um kinetic energy.
  • As the object falls towards the ground the potential energy is being converted to kinetic energy.
  • Therefore, the potential energy at the beginning will be equal to the kinetic energy at the end when the object is on the ground.
  • We can therefore, conclude that, (PE)beginning = (KE)end
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A 5.31 kg object is swung in a vertical circular path on a string 2.99 m long. The acceleration of gravity is 9.8 m/s 2 . If the
11111nata11111 [884]

Answer:

T = 120.3 N

Explanation:

Since, the tension in the rope is acting against both the centripetal force and the weight of the stone. As both act downward towards center of the circle and tension acts towards point of support that is upward. So, tension will be equal to the sum of centripetal force and weight of the stone:

Tension = Centripetal Force + Weight of Stone

T = mv²/r + mg

where,

m = mass of stone = 5.31 kg

r = radius of circle = length of string = 2.99 m

g = 9.8 m/s²

Therefore,

T = (5.31 kg)(6.2 m/s)²/(2.99 m) + (5.31 kg)(9.8 m/s²)

T = 68.27 N + 52.03 N

<u>T = 120.3 N</u>

4 0
3 years ago
What will be the pressure exerterd by the 0bject if 4000n is acting on an area of 50msqure
Ivahew [28]
<h3>Given, </h3>

Force,F = 4000 N

Area,a = 50 m²

<h3>We know that, </h3>

Pressure = Force/Area

★ Putting the values in the above formula,we get:

\sf \rightarrow \: pressure =  \dfrac{4000}{50}

\sf \rightarrow pressure = 80 \: N {m}^{ - 2}

7 0
3 years ago
A wire carrying a 29.0 A current passes between the poles of a strong magnet such that the wire is perpendicular to the magnet's
Dmitrij [34]

Answer:

2.59 T

Explanation:

Parameters given:

Current flowing through the wire, I = 29 A

Angle between the magnetic field and wire, θ = 90°

Magnetic force, F = 2.25 N

Length of wire, L = 3 cm = 0.03 m

The magnetic force, F, is related to the magnetic field, B, by the equation below:

F = I * L * B * sinθ

Inputting the given parameters:

2.25 = 29 * 0.03 * B * sin90

2.25 = 0.87 * B

=> B = 2.25/0.87

B = 2.59 T

The magnetic field strength between the poles is 2.59 T

4 0
3 years ago
How light is channelled down an optical fibre
coldgirl [10]

Explanation:

Suppose you want to shine a flashlight beam down a long, straight hallway. Just point the beam straight down the hallway -- light travels in straight lines, so it is no problem. What if the hallway has a bend in it? You could place a mirror at the bend to reflect the light beam around the corner. What if the hallway is very winding with multiple bends? You might line the walls with mirrors and angle the beam so that it bounces from side-to-side all along the hallway. This is exactly what happens in an optical fiber.

The light in a fiber-optic cable travels through the core (hallway) by constantly bouncing from the cladding (mirror-lined walls), a principle called total internal reflection. Because the cladding does not absorb any light from the core, the light wave can travel great distances.

However, some of the light signal degrades within the fiber, mostly due to impurities in the glass. The extent that the signal degrades depends on the purity of the glass and the wavelength of the transmitted light (for example, 850 nm = 60 to 75 percent/km; 1,300 nm = 50 to 60 percent/km; 1,550 nm is greater than 50 percent/km). Some premium optical fibers show much less signal degradation -- less than 10 percent/km at 1,550 nm.

1

3 0
3 years ago
Magnetic fields exist
Effectus [21]

Answer:

Magnetic fields exist near a magnet, farther away from a magnet, and within a magnet.

So, the answer is D. All of the above.

Let me know if this helps!

6 0
3 years ago
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