Answer:
Explanation:
Assume the rod is horizontal
Sum vertical forces to zero
F - 8 - 4 - 2 - 3 = 0
F = 17 N
While this result answers precisely the question asked, it is not sufficient to guarantee equilibrium. We must also locate this force by summing moments to zero. Let's choose to sum about the left end.
8[9/2] + 4[1] + 2[6] + 3[4] - 17[x] = 0
x = 3.76470588...
the force must be supplied upward approximately 3.765 m from the left end
The rod does not actually have to be horizontal. Moment arms will all be proportionately reduced by tilting the bar from horizontal and the results will be identical. Assuming horizontal just reduces the calculation effort.
Complete Question
One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. Having recently studied optics in your physics class, you're not too surprised to see that the patch of light seems to be a circular diffraction pattern. It appears that the central maximum is about 2 cm across, and you estimate that the distance from the window shade to the wall is about 5 m.
Required:
Estimate the diameter of the pinhole.
Answer:
The diameter is 
Explanation:
From the question we are told that
The central maxima is 
The distance from the window shade is 
The average wavelength of the sun is mathematically evaluated as
Generally the visible light spectrum has a wavelength range between 400 nm to 700 nm
So the initial wavelength of the sun is 
and the final wavelength is 
Substituting this into the above equation
The diameter is evaluated as
substituting values
1. The problem statement, all variables and given/known data A screw jack has a single start thread of pitch 7mm and a operating handle 800mm long.when raising a load of 750kg the effort required on thev end of the handle is 26N. determine for these operating conditions the following : (a) the mechanical advantage (b) the velocity ratio (c) the efficiency of the machine (d) the law of the machine 2. Relevant equations ma = load/effort vr = 2 x pie x r/p effiency of the machine = ma/vr x 100% law of the machine = E = aw+b 3. The attempt at a solution (a) mechanical advantage = 750 x 9.81/26N = 282.98 (b) the velocity ratio = 2 x pie x 800mm/7mm = 718.07 (c) the effiency of the machine = 282.98/718.07 x 100% = 39.40% (d) the law of the machine this is where i am struggling i no the formula is E = aw+b where a is the velocity ratio and w is the load however what does the b stand for and if i need to caculate this how do i do this please help ......
