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3 years ago

Which statement best describes how waves carry energy?

Physics

2 answers:

ratelena [41]3 years ago

7 0

Correct answer choice is :

A) Energy moves from one place to another through the wave.

Explanation:

Waves can carry energy over a range without moving matter the complete distance. For instance, an ocean wave can move many kilometers without the water itself traveling many kilometers. The water moves up and down a motion recognized as a disturbance. A wave brings its energy without carrying matter. Waves are observed to travel through an ocean or lake, yet the water perpetually reverts to its rest state. Energy is carried through the medium, yet the water particles are not carried.

nignag [31]3 years ago

5 0

A.Energy moves from one place to another through the wave.

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An athlete at the gym holds a 3.0 kg steel ball in his hand. His arm is 60 cm long and has a mass of 3.8 kg, with the center of

Serggg [28]

Answer:

(a) τ = 26.58 Nm

(b) τ = 18.79 Nm

Explanation:

(a)

First we find the torque due to the ball in hand:

τ₁ = F₁d₁

where,

τ₁ = Torque due to ball in hand = ?

F₁ = Force due to ball in hand = m₁g = (3 kg)(9.8 m/s²) = 29.4 N

d₁ = perpendicular distance between ball and shoulder = 60 cm = 0.6 m

τ₁ = (29.4 N)(0.6 m)

τ₁ = 17.64 Nm

Now, we calculate the torque due to the his arm:

τ₁ = F₁d₁

where,

τ₂ = Torque due to arm = ?

F₂ = Force due to arm = m₂g = (3.8 kg)(9.8 m/s²) = 37.24 N

d₂ = perpendicular distance between center of mass and shoulder = 40% of 60 cm = (0.4)(60 cm) = 24 cm = 0.24 m

τ₂ = (37.24 N)(0.24 m)

τ₂ = 8.94 Nm

Since, both torques have same direction. Therefore, total torque will be:

τ = τ₁ + τ₂

τ = 17.64 Nm + 8.94 Nm

τ = 26.58 Nm

(b)

Now, the arm is at 45° below horizontal line.

First we find the torque due to the ball in hand:

τ₁ = F₁d₁

where,

τ₁ = Torque due to ball in hand = ?

F₁ = Force due to ball in hand = m₁g = (3 kg)(9.8 m/s²) = 29.4 N

42.42 cm = 0.4242 m

τ₁ = (29.4 N)(0.4242 m)

τ₁ = 12.47 Nm

Now, we calculate the torque due to the his arm:

τ₁ = F₁d₁

where,

τ₂ = Torque due to arm = ?

F₂ = Force due to arm = m₂g = (3.8 kg)(9.8 m/s²) = 37.24 N

d₂ = perpendicular distance between center of mass and shoulder = 40% of (60 cm)(Cos 45°) = (0.4)(42.42 cm) = 16.96 cm = 0.1696 m

τ₂ = (37.24 N)(0.1696 m)

τ₂ = 6.32 Nm

Since, both torques have same direction. Therefore, total torque will be:

τ = τ₁ + τ₂

τ = 12.47 Nm + 6.32 Nm

τ = 18.79 Nm

3 0

2 years ago

The wattage of a bulb is 24 W when it is connected to a 12 V battery. Calculate its effective wattage if it operates on a 6 V ba

tresset_1 [31]

It would be 12W because: 6v is half of 12v so half of 24w would be 12w

3 0

2 years ago

Read 2 more answers

PLEASE HELP ASAP!!

Stells [14]

Its B: reduce the amount of energy needed to do the work by putting the work onto something else

3 0

3 years ago

Read 2 more answers

What's the frequency of a wave with a wavelength of 10 and velocity of 200m/s?

uranmaximum [27]

Answer:

$\boxed {\boxed {\sf 20 \ Hz}}$

Explanation:

The frequency of a wave can be found using the following formula.

$f=\frac{v}{\lambda}$

where f is the frequency, v is the velocity/wave speed, and λ is the wavelength.

The wavelength is 10 meters and the velocity is 200 meters per second.

1 m/s can also be written as 1 m*s^-1

Therefore:

$v= 200 \ m*s^{-1} \\\lambda = 10 \ m$

Substitute the values into the formula.

$f=\frac{200 \ m*s^{-1}}{10 \ m}$

Divide and note that the meters (m) will cancel each other out.

$f=\frac{200 \ s^{-1}}{10 \ }$

$f=20 \ s^{-1}$

1 s^-1 is equal to Hertz
Therefore, our answer of 20 s^-1 is equal to 20 Hz

$f= 20 \ Hz$

The frequency of the wave is 20 Hertz

7 0

2 years ago

An elaborate pulley consists of four identical balls at the ends of spokes extending out from a rotating drum. A box is connecte

Klio2033 [76]

Answer:

its speed will be less than V

Explanation:

When the ball falls a distance d, its final kinetic energy plus rotational kinetic energy of the drum equals its initial potential energy.

K = U

With its speed V at the end of d, we have

1/2mV² + 1/2Iω² = mgd where I = rotational inertia of drum and balls, ω = angular speed of drum and balls and m = mass of box

1/2mV² + 1/2Iω² = mgd

1/2mV² = mgd - 1/2Iω²

V² = [2(mgd - 1/2Iω²)/m]

V = √[2(mgd - 1/2Iω²)/m]

When the four balls are moved inward closer to the drum, their rotational inertia increases and also its angular speed which thus causes an increase in rotational kinetic energy. But, since the box still falls the same distance of d, its final kinetic energy plus rotational kinetic energy of the drum plus balls still equals its initial potential energy

K = U

I' = new rotational inertia of drum and balls, ω' = new angular speed of drum and balls

With its new speed is now V' at the end of d,

1/2mV'² + 1/2I'ω'² = mgd

1/2mV'² = mgd - 1/2I'ω'²

V² = [2(mgd - 1/2I'ω'²)/m]

V' = √[2(mgd - 1/2I'ω'²)/m]

Since I' and ω' increase, the rotational kinetic energy of the drum and balls (1/2I'ω'²) increases. Thus, the difference (mgd - 1/2I'ω'²) < (mgd - 1/2Iω²) which implies that the kinetic energy of the box decreases. Hence, since its kinetic energy decreases, its speed V' also decreases.

So, V' < V

So, its speed will be less than V.

3 0

3 years ago