Answer:
Explanation:
f
=
v
λ
where v is the velocity of the wave
λ
is the wavelength.
Wavelength = (speed)/(frequency) = 300,000,000/120,000,000 = 2.5 meters
Let the key is free falling, therefore from equation of motion
.
Take initial velocity, u=0, so
.
As velocity moves with constant velocity of 3.5 m/s, therefore we can use formula
From above substituting t,
.
Now substituting all the given values and g = 9.8 m/s^2, we get
.
Thus, the distance the boat was from the point of impact when the key was released is 10.60 m.
Answer:
T = 27.92 N
Explanation:
For this exercise let's use Newton's second law
T - W = m a
The weight
W = mg
The acceleration can be found by derivatives
a = dv / dt
v = 2 t + 0.6 t²
a = 2 + 0.6 t
We replace
T - mg = m (2 + 0.6t)
T = m (g + 2 + 0.6 t) (1)
Let's look for the time for the speed of 15 m / s
15 = 2 t + 0.6 t²
0.6 t² + 2 t - 15 = 0
We solve the second degree equation
t = [-2 ±√(4 - 4 0.6 (-15))] / 2 0.6
t = [-2 ±√40] / 1.3 = [-2 ± 6.325] / 1.2
We take the positive time
t = 3.6 s
Let's calculate from equation 1
T = 2.00 (9.8 + 2 + 0. 6 3.6)
T = 27.92 N
-- The net effective resistance of three 1200-ohm resistors in
parallel is (1200/3) = 400 ohms. That's what the battery sees.
-- Power = (voltage)² / (resistance)
= (12²) / (400)
= 144 / 400
= 0.36 watt .
There's no such thing as "power in the circuit".
0.36 watt is the power dissipated by the resistors.
It's the rate at which the battery must supply energy,
and the rate at which the resistors blow it off in the form
of heat, for as long as the battery lasts.