<span>(a) How fast is it moving when it reaches 12.0 m?
To determine the velocity as it reaches 12.0 m, we use one of the kinematic equations,
</span>V^2 = Vo^2 + 2gh
<span>where Vo = 20 m/s. </span>
<span> g = -9.8 m/s^2 </span>
<span> h = 12.0 m. </span>
V^2 = 20^2 + 2(-9.8)(12.0)
<span>V^2 = 164.8
V = 12.84 m/s
(b) How long is required to reach this height?
To determine the maximum height, we use the same equation we used above,
</span>V^2 = Vo^2 + 2gh
where Vo = 20 m/s.
g = -9.8 m/s^2
V = 0 (since at the maximum height velocity is zero)
0^2 = 20^2 + 2(-9.8)h
<span>h = 20.41 m
(c) Why are there two answers for (b)?
There are two answers for b because it would travel a distance up and travel a distance down.</span>
Answer:
I₁/I₂ = 1000
Thus, the sound of siren is 1000 times louder than the sound of wolf's howl.
Explanation:
First, we need to calculate the intensity of both the sounds. The formula for sound level is given as:
L = 10 log[I/I₀]
where,
L = Sound Level in dB
I = Intensity of sound
I₀ = Reference intensity = 10⁻¹² W/m²
<u>FOR SOUND OF SIREN:</u>
L = 120 dB
I = I₁ = ?
Therefore,
120 = 10 log[I₁/10⁻¹²]
log[I₁/10⁻¹²] = (120)/10
log[I₁/10⁻¹²] = 12
I₁/10⁻¹² = 10¹²
I₁ = (10¹²)(10⁻¹²)
I₁ = 1
<u>FOR SOUND OF WOLF'S HOWL:</u>
L = 90 dB
I = I₂ = ?
Therefore,
90 = 10 log[I₂/10⁻¹²]
log[I₂/10⁻¹²] = (90)/10
log[I₂/10⁻¹²] = 9
I₂/10⁻¹² = 10⁹
I₂ = (10⁹)(10⁻¹²)
I₂ = 10⁻³
Now, we divide the intensities:
I₁/I₂ = 1/10⁻³
I₁/I₂ = 10³
<u>I₁/I₂ = 1000</u>
<u>Thus, the sound of siren is 1000 times louder than the sound of wolf's howl.</u>
8). A rubber band is storing more elastic energy in it when it's stretched.
It's the work you had to do to stretch it.
9). Radio, TV, microwave, infrared (heat), visible light, ultraviolet light, X-rays,
and gamma rays are all part of the electromagnetic spectrum, and all of them
carry energy from one place to another.
Answer:
3.90 degrees
Explanation:
Let g= 9.81 m/s2. The gravity of the 30kg grocery cart is
W = mg = 30*9.81 = 294.3 N
This gravity is split into 2 components on the ramp, 1 parallel and the other perpendicular to the ramp.
We can calculate the parallel one since it's the one that affects the force required to push up
F = WsinΘ
Since customer would not complain if the force is no more than 20N
F = 20
So the ramp cannot be larger than 3.9 degrees
The first living being to make an orbital spaceflight around the Earth was the dog Laika, aboard the Soviet spacecraft Sputnik 2 on 3 November 1957.
