Answer:
T=3.29 N
Explanation:
let V be the speed at low point
From conservation of energy
0.5mV²=m*g*l*(1-cos(∅))
(mV²/l)=2m*g*(1-cos(∅))
Nowat low point
T-mg=mV²/l
T=mg+2mg((1-cos(∅))
T=mg(3-2cos(∅))
T=0.25*.81*(3-2cos(34))
T=3.29 N
Answer:
The magnitude of their velocities will be the same but their direction will be reversed.
Answer:
(a) Approximately 968 Hz.
Explanation:
The observed frequency is less than 1003 Hz because of Doppler's Effect. When the source is moving away from an observer that doesn't move, the equation for the observed frequency would be:
,
where in the context of this problem,
- is the speed of sound in the air.
- is the speed at which the source moves away from the observer.
- is the frequency at the source.
Apply this equation to find :
.
Here's an alternative explanation.
The frequency of the siren at the source is . That corresponds to a period of .
In other words, at the source, a peak arrives about every .
The source is moving away from the observer at a speed of . In the between the first and the second peak, the source moved away from the observer. It would take an extra for the sound to cover that extra distance.
As a result, the period of the sound would appear to be to the observer.
That corresponds to an observed frequency of . (Same as the answer from the formula.)
Answer:
Correct answer: Ic₂ = 48 mA = 48 · 10⁻³ A
Explanation:
Given:
U₁ = 12 V DC first battery voltage
Ic₁ = 24 mA = 24 · 10⁻³ A Intensity of current with the first battery
U₂ = 24 V DC second battery voltage
Ic₂ = ? Intensity of current with the second battery
The formula that applies to a simple electric circuit under the Ohm's law is:
R = U / Ic
where R is the total resistance in the electrical circuit and it is constant.
R = U₁ / Ic₁ = U₂ / Ic₂ ⇒ U₁ / Ic₁ = U₂ / Ic₂ ⇒ Ic₂ = (U₂ · Ic₁) / U₁
Ic₂ = (24 · 24) / 12 = 48 mA
Ic₂ = 48 mA = 48 · 10⁻³ A
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