Answer: 9
Explanation:
Kinetic energy is the energy possessed by a moving object. It is measured in joules, and depends on the mass (m) of the object and the speed (v) by which it moves i.e K.E = 1/2 x mass x velocity^2
So, car is traveling 120 km/h
KE = 1/2x m x (120 km/h)^2
KE = 0.5 x m x 14400
KE1 = 7200m
So, car is traveling 40 km/h
KE = 1/2x m x (40 km/h)^2
KE = 0.5 x m x 1600
KE2 = 800m
Now, divide the value of kinetic energy obtained during 120 km/h by that obtained during 40 km/h
i.e 7200m / 800m
= 9
Thus, the kinetic energy will be 9 times more at a speed of 120 km/h than at 40 km/h
Answer:
1) λ = 24.7 cm, 2) f = 13.88 Hz, 3) L = 117.3 cm
Explanation:
1) This is a resonance process, that is, the wave going downwards will interfere with the wave going upwards.
This is a tube with one end closed and the other open, at the closed end there is a node and at the open end a belly, so the resonances are
L = λ / 4
λ = 4L 1st harmonic
λ = 4L / 3 third harmonic
λ = 4L / 5 fifth harmonic
λ = 4L / n ’ n’ odd number n ’= (2n +1)
the wavelength is requested for the eighth resonance n = 8, the corresponding prime number is
n ’= 2 8 +1
n ’= 17
we substitute
λ = 4 105/17
λ = 24.7 cm
2) the speed of the wave is related to the wavelength and frequency
v = λf
f = v /λ
f = 343 / 24.7
f = 13.88 Hz
3) the next resonance occurs for n = 9, so the prime number is
n ’= 2 9 +1
n ’= 19
L = n’ λ / 4
L = 19 λ / 4
We must suppose a value for the wavelength, if the wavelength is present in the tube and the length of the column increases, the resonance number increases
L = 19 24.7/4
L = 117.3 cm
Answer:
Hz
Explanation:
In alternating current (AC) circuits, voltage (V) oscillates in a sine wave pattern and has a general equation as a function of time (t) as follows;
V(t) = V sin (ωt + Ф) -----------------(i)
Where;
V = amplitude value of the voltage
ω = angular frequency = 2 π f [f = cyclic frequency or simply, frequency]
Ф = phase difference between voltage and current.
<u><em>Now,</em></u>
From the question,
V(t) = 230 sin (100t) ---------------(ii)
<em><u>By comparing equations (i) and (ii) the following holds;</u></em>
V = 230
ω = 100
Ф = 0
<em><u>But;</u></em>
ω = 2 π f = 100
2 π f = 100 [divide both sides by 2]
π f = 50
f = Hz
Therefore, the frequency of the voltage is Hz
