Answer:
A book on its side exerts a greater force.
Explanation:
Pressure = Force / Area
Assuming that 1kg = 10N
2kg = 20N
Area of book lying flat = 0.3m × 0.2m
= 0.6m²
Pressure of book lying flat = 20N / 0.6m²
= 30Pa (1 s.f.)
Area of book on its side = 0.2m × 0.05m
= 0.01m²
Pressure of book on its side = 20N / 0.01m²
= 2000Pa (1 s.f.)
Since 2000Pa (1 s.f.) > 30Pa (1 s.f.), a book on its side applies greater pressure than lying flat.
Answer:
Explanation:
Conduction of heat through a thick layer is governed by the following relation
Q = KA( T₂ -T₁ ) / d
K is thermal conductivity of medium ( it is earth here ) , A is surface area though which heat conducts and T₂ -T₁ is temperature difference and d is thickness of medium through which heat conducts.
k = 8 units
A = surface area= 2πrL
= 2x 3.14 x 2/12 x 100
= 104.67 ft²
T₂ -T₁ = 70 - 42
= 28 F
d = thickness
= 30 /12 ft
= 2.5 ft
Putting the given values here
Q =
= 9378.4 Btu per hour.
Answer:
The frequency the motorcyclist hears is 601.60 Hz
Explanation:
The Doppler effect is a physical phenomenon where an apparent change in wave frequency is presented by a sound source with respect to its observer.
The following expression is considered the general case of the Doppler effect:
Where:
f ’, f: Frequency perceived by the receiver and frequency emitted by the emitter respectively. Its unit of measurement in the International System (S.I.) is hertz (Hz), which is the inverse unit of the second (1 Hz = 1 s-1)
v: propagation speed of the wave in the medium. It is constant and depends on the characteristics of the medium. In this case, the speed of sound in air is considered to be 34o m / s
vR, vE: Receiver and emitter speed respectively. Your unit of measure in the S.I. is the m / s
±, ∓:
The + sign is used:
- In the numerator if the receiver approaches the sender
.
- In the denominator if the emitter moves away from the receiver
.
The sign - is used:
- In the numerator if the receiver moves away from the sender
.
- In the denominator if the emitter approaches the receiver.
In this case:
- f: 523 Hz:
- v= 340 m/s
- vR= 13.6 m/s
- vE= 32.6 m/s
-
The emitter approaches the receiver, so the + sign is used in the numerator and the - sign is used in the denominator.
Replacing:
Solving:
f' = 601.60 Hz
<u><em>
The frequency the motorcyclist hears is 601.60 Hz</em></u>
You haven't listed any choices or offered any suggested answers.
So there's no way for us to guide you to select the correct one, and
if I want to answer this question and scoop up a few points, I have to
invent an answer from scratch.
On a speed/time graph, a VERTICAL line segment represents something
that's physically impossible.
The top of the line segment is a speed that's faster than the bottom
of the segment, but the times are both the same.
A change of speed that takes no time would correspond to infinite
acceleration. That just simply sounds wrong, and it is. Can't happen.
Answer:
72.04 dB.
Explanation:
The intensity level of 60dB corresponds to the sound intensity given by the equation
where
solving for we get:
Now, when 16 violins are playing the intensity becomes
which on the decibel scale gives
.
Thus, playing 16 violins together gives the intensity level of 72 dB.