Answer:D: the velocity is zero
Explanation:
From the planks equation
E=hv
V= c/ wave length
V= 3×10^8/30×10^-9
=1×10^16
E= hv
6.63×10^-34×1×10^16
= 6.63×10^-18
Using the given formula with v0=56 ft/s and h=40 ft
h = -16t2 + v0t
40 = -16t2 + 56t
16t2 - 56t + 40 = 0
Solving the quadratic equation:
t= (-b+/-(b^2-4ac)^1/2)/2a = (56+/-((-56)^2-4*16*40)^1/2)/2*16 = (56 +/- 24) / 32
We have two possible solutions
t1 = (56+24)/32 = 2.5
t2 = (56-24)/32 = 1
So initially the ball reach a height of 40 ft in 1 second.
Answer:
Hello
a) the change of velocity over time
Explanation:
Power is current times voltage.
P = IV
And from Ohm's law, voltage is current times resistance.
V = IR
So if we solve for I in Ohm's law and substitute into the power equation:
I = V/R
P = (V/R) V
P = V² / R
Given that P = 7 W and V = 7 V:
7 = 7² / R
R = 7 Ω
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