Answer:
a) W_total = 8240 J
, b) W₁ / W₂ = 1.1
Explanation:
In this exercise you are asked to calculate the work that is defined by
W = F. dy
As the container is rising and the force is vertical the scalar product is reduced to the algebraic product.
W = F dy = F Δy
let's apply this formula to our case
a) Let's use Newton's second law to calculate the force in the first y = 5 m
F - W = m a
W = mg
F = m (a + g)
F = 80 (1 + 9.8)
F = 864 N
The work of this force we will call it W1
We look for the force for the final 5 m, since the speed is constant the force must be equal to the weight (a = 0)
F₂ - W = 0
F₂ = W
F₂ = 80 9.8
F₂ = 784 N
The work of this fura we will call them W2
The total work is
W_total = W₁ + W₂
W_total = (F + F₂) y
W_total = (864 + 784) 5
W_total = 8240 J
b) To find the relationship between work with relate (W1) and work with constant speed (W2), let's use
W₁ / W₂ = F y / F₂ y
W₁ / W₂ = 864/784
W₁ / W₂ = 1.1
Larry Finkelstein, Norman Fischer, and Cassius Schwartz have been overlooked, in my opinion.
Answer:
16.77 m/s
Explanation:
Given that
Frequency of middle pitch, Fo = 261.6 Hz
Frequency of C sharp, f = 277.2 Hz
Velocity of sound in air, v = 298 m/s
Speed of sound from the source, Vs = ? m/s
Using the formula
f = Fo•(V + Vr)/(V + Vs)
← Doppler
Vr would be +ve if the receiver is moving toward source;
Vs would be -ve if source is moving toward the receiver
277.2 Hz = 261.6Hz * (298 + 0) / (298 - Vs)
277.2 = 77956.8 / (298 - Vs)
298 - Vs = 77956.8 / 277.2
298 - Vs = 281.23
Vs = 298 - 281.23
Vs = 16.77 m/s
Thus, the speed needed is 16.77 m/s
I made the drawing in the attached file.
I included two figures.
The upper figure shows the effect of:
- multiplying vector A times 1.5.
It is drawn in red with dotted line.
- multiplying vector B times - 3 .
It is drawn in purple with dotted line.
In the lower figure you have the resultant vector: C = 1.5A - 3B.
The method is that you translate the tail of the vector -3B unitl the point of the vector 1,5A, preserving the angles.
Then you draw the arrow that joins the tail of 1,5A with the point of -3B after translation.
The resultant arrow is the vector C and it is drawn in black dotted line.