Let
upthrust = T
weight = W = mg
Air resistance = F
When balloon is descending, air resistance acts upwards (positive)
By Newton's first law, the net force on the balloon is zero, or
T+F-W=0......................(1)
Let w=weight of material dumped so that balloon now travels upwards at constant speed.
Air resistance acts against motion, namely downwards.
The Newton's equation now reads
T-F-(W-w)=0................(2)
Subtract (2) from (1)
T+F-W - (T-F-(W-w)) = 0
Solve for w
w=2F, or
the WEIGHT of material to be released equals twice the resistance of air.
<span>E = h x f </span>
<span>. . . then : </span>
<span>f = E / h </span>
<span>f = 4,41•10^-19 / 6,62•10^-34 </span>
<span>f = 6,66•10^14 Hz (s^-1) </span>
<span>b/ What is the wavelength of this light ? </span>
<span>- - - - - - - - - - - - - - - - - - - - - - - - - - - - </span>
<span>λ = c / f </span>
<span>λ = 3•10^8 / 6,66•10^14 </span>
<span>λ = 4,50•10^-7 m </span>
Answer:
v = 1/3 m / s = 0.333 m / s
in the direction of the truck
Explanation:
The average speed is defined by the variation of the position between the time spent
v = Δx / Δt
since the position is a vector we must add using vectors, we will assume that the displacement to the right is positive, the total displacement is
Δx = 20 - 15 +20
Δx = 25 m
therefore we calculate
v = 25/75
v = 1/3 m / s = 0.333 m / s
in the direction of the truck
~Formula: Voltage= current• resistance
(V= Ir)
~Using this formula, plug in the numbers from the equation into the formula
~5=25i
~Now you have a one-step equation
~Divide by 25 on both sides and you should get your answer:
~I= 0.2 (which means current is 0.2)
