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4 years ago

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Physics

1 answer:

Artemon [7]4 years ago

7 0

Explanation:

At a height of 93 m, the gravitational potential energy is given by :

P = mgh

Where, m is the mass of a penny

We can find its mass.

$m=\dfrac{P}{gh}\\\\m=\dfrac{3}{9.8\times 93}\\\\m=0.00329\ kg$

We need to find how much potential energy will have transformed into kinetic energy at the half way point (46.5m). It can be calculated as :

$E=mgh'\\\\E=0.00329\times 9.8\times 46.5\\\\E=1.499\ J$

Hence, a penny will have transferred 1.499 J of potential energy into kinetic energy.

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A projectile is launched straight upward at 50 m/s. Neglecting air resistance its speed upon returning to its starting point is:

lbvjy [14]

Answer:

The speed of the projectile upon returning to its starting point is 50 m/s.

Explanation:

Given;

initial velocity of the projectile, u = 50 m/s

The velocity of the projectile is maximum before hitting the ground. As the object moves upward, the velocity reduces as it approaches the maximum height, at the maximum height the velocity becomes zero. Also, as the object moves downward, the velocity starts to increase and becomes maximum before hitting the ground.

Therefore, the speed of the projectile upon returning to its starting point is 50 m/s.

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3 years ago

Why are the spheres representing nitrogen and oxygen different colors

erastovalidia [21]

Spheres representing nitrogen and oxyfgen are different colors so you can easily tell them apart.

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3 years ago

The force that keeps two surfaces at rest from sliding over each other is

natka813 [3]

Friction is the correct answer.

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3 years ago

0.0010 kg pellet is fired at a speed of 52.2 m/s at a motionless 3.3 kg piece of balsa wood. When the pellet

Paraphin [41]

The formula for momentum is p = m*v

The conservation of momentum suggests:

m*vi = m*vf (initial mass times initial velocity = final mass times final velocity or initial momentum = final momentum)

(0.0010)(52.2) = (0.0010 + 3.3)vf

vf = (0.0010)(52.2)/(0.0010 + 3.3) = 0.0522/3.301 ≈ 0.01581 m/s

To the nearest thousandth ≈ .016 m/s

7 0

3 years ago

A normal mode of a closed system is an oscillation of the system in which all parts oscillate at a single frequency. In general

valentina_108 [34]

Answer:

Explanation:

(A)

The string has set of normal modes and the string is oscillating in one of its modes.

The resonant frequencies of a physical object depend on its material, structure and boundary conditions.

The free motion described by the normal modes take place at the fixed frequencies and these frequencies is called resonant frequencies.

Given below are the incorrect options about the wave in the string.

• The wave is travelling in the +x direction

• The wave is travelling in the -x direction

• The wave will satisfy the given boundary conditions for any arbitrary wavelength $\lambda_i$

• The wave does not satisfy the boundary conditions $y_i(0;t)=0
$

Here, the string of length L held fixed at both ends, located at x=0 and x=L

The key constraint with normal modes is that there are two spatial boundary conditions, $y(0,1)=0
$

and $y(L,t)=0$

.The spring is fixed at its two ends.

The correct options about the wave in the string is

• The wavelength $\lambda_i$ can have only certain specific values if the boundary conditions are to be satisfied.

(B)

The key factors producing the normal mode is that there are two spatial boundary conditions, $y_i(0;t)=0$ and $y_i(L;t)=0$ , that are satisfied only for particular value of $\lambda_i$ .

Given below are the incorrect options about the wave in the string.

• $A_i$ must be chosen so that the wave fits exactly o the string.

• Any one of $A_i$ or $\lambda_i$ or $f_i$ can be chosen to make the solution a normal mode.

Hence, the correct option is that the system can resonate at only certain resonance frequencies $f_i$ and the wavelength $\lambda_i$ must be such that $y_i(0;t) = y_i(L;t)=0
$