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2 years ago

What is the SI unit for intensity?

Physics

1 answer:

Allisa [31]2 years ago

8 0

Answer:

The SI unit of intensity is the watt per square meter/metre (W/m^2.)

Explanation:

Intensity is equal to the power transferred per unit area. Since power is measured in watts (W) and 1 W = 1 J/s, then intensity can be viewed as how fast energy goes through a certain area.

In physics, intensity is often used when studying light, sound, or other phenomena that involve waves or energy transfer. (With waves, the power value is taken as the average power transfer over the wave's period.)

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A particle with a mass of 0.500 kg is attached to a horizontal spring with a force constant of 50.0 N/m. At the moment t = 0, th

svp [43]

a) $x(t)=2.0 sin (10 t) [m]$

The equation which gives the position of a simple harmonic oscillator is:

$x(t)= A sin (\omega t)$

where

A is the amplitude

$\omega=\sqrt{\frac{k}{m}}$ is the angular frequency, with k being the spring constant and m the mass

t is the time

Let's start by calculating the angular frequency:

$\omega=\sqrt{\frac{k}{m}}=\sqrt{\frac{50.0 N/m}{0.500 kg}}=10 rad/s$

The amplitude, A, can be found from the maximum velocity of the spring:

$v_{max}=\omega A\\A=\frac{v_{max}}{\omega}=\frac{20.0 m/s}{10 rad/s}=2 m$

So, the equation of motion is

$x(t)= 2.0 sin (10 t) [m]$

b) t=0.10 s, t=0.52 s

The potential energy is given by:

$U(x)=\frac{1}{2}kx^2$

While the kinetic energy is given by:

$K=\frac{1}{2}mv^2$

The velocity as a function of time t is:

$v(t)=v_{max} cos(\omega t)$

The problem asks as the time t at which U=3K, so we have:

$\frac{1}{2}kx^2 = \frac{3}{2}mv^2\\kx^2 = 3mv^2\\k (A sin (\omega t))^2 = 3m (\omega A cos(\omega t))^2\\(tan(\omega t))^2=\frac{3m\omega^2}{k}$

However, $\frac{m}{k}=\frac{1}{\omega^2}$ , so we have

$(tan(\omega t))^2=\frac{3\omega^2}{\omega^2}=3\\tan(\omega t)=\pm \sqrt{3}\\$

with two solutions:

$\omega t= \frac{\pi}{3}\\t=\frac{\pi}{3\omega}=\frac{\pi}{3(10 rad/s)}=0.10 s$

$\omega t= \frac{5\pi}{3}\\t=\frac{5\pi}{3\omega}=\frac{5\pi}{3(10 rad/s)}=0.52 s$

c) 3 seconds.

When x=0, the equation of motion is:

$0=A sin (\omega t)$

so, t=0.

When x=1.00 m, the equation of motion is:

$1=A sin(\omega t)\\sin(\omega t)=\frac{1}{A}=\frac{1}{2}\\\omega t= 30\\t=\frac{30}{\omega}=\frac{30}{10 rad/s}=3 s$

So, the time needed is 3 seconds.

d) 0.097 m

The period of the oscillator in this problem is:

$T=\frac{2\pi}{\omega}=\frac{2\pi}{10 rad/s}=0.628 s$

The period of a pendulum is:

$T=2 \pi \sqrt{\frac{L}{g}}$

where L is the length of the pendulum. By using T=0.628 s, we find

$L=\frac{T^2g}{(2\pi)^2}=\frac{(0.628 s)^2(9.8 m/s^2)}{(2\pi)^2}=0.097 m$

5 0

3 years ago

Diane swim 5 kilometers against the current in the same amout of time it took her to swim 15 kilometers with the current . The r

lidiya [134]

Answer:

4 km/hr

Explanation:

suppose 's' is Diane's speed with no current.

't' represents time in hrs.

Using the formula:

Distance = speed 's' x time 't'

-> when she swims against the current, equation will be,

5= (s-2)t

t= 5/(s-2)

->when she was swimming with the current, equation is,

15= (s+2) t

t= 15/(s+2)

equating eq(1) and (2)

5/(s-2) = 15/(s+2)

5s + 10 = 15s - 30

40= 10s

s= 40/10

s=4

Therefore, if there were no current, her speed is 4km/hr

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3 years ago

Q 1. Choose the correct answer.

Natalija [7]

Answer:

Dietz

Explanation:

He is the guy you must justt be smart and know stuff.

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2 years ago

Which of the following is a vector quantity?

gizmo_the_mogwai [7]

Answer:

B. 30 m down

Explanation:

In physics we have two types of quantities:

- Scalar quantity: it is a quantity which only has a magnitude (e.g: mass and time are scalar quantities, since they only have a magnitude)

- Vector quantity: it is a quantity which has both a magnitude and a direction (e.g: velocity is a vector quantity, since it has a magnitude (the speed) and a direction)

In this problem, we have:

A. 100 ounces of water --> scalar (this is a volume, which has only a magnitude)

B. 30 m down --> vector (this is a displacement, which has both a magnitude (30 m) and a direction (down)

C. 88 mi/s --> scalar (this is a speed, which has only a magnitude)

D. 45 gallons in a bucket --> scalar (this is a volume, which has only a magnitude)

So, the correct option is B.

4 0

3 years ago

An airplane is heading due north. It experiences a crosswind in the westerly direction. What is the direction of travel for the

Sergeeva-Olga [200]

The direction is something between west and north. That is, a heading between 270 and 360. The exact direction depends on the airplane's airspeed and the wind speed.

6 0

3 years ago

Read 2 more answers