Great experiment ! Everybody should try it if they can get the equipment.
It demonstrates a lot of things that are very hard to explain in words.
I hope the students remembered to tilt the axis of the globe. If they didn't,
and instead kept it straight up and down, then each city had pretty much
the same amount of bulb-light all the way around, and there were no seasons.
If the axis of the globe was tilted, then City-D had the least variation in
seasons. City-D is only 2° from the equator, so the sun is more direct
there all year around than it is at any of the others.
A) 50 cm
B) 10000 cm/s
Explanation
Step 1
A)
If you know the distance between nodes and antinodes then use this equation:

then, let

now, replace to find the wavelength

so, the wavelength is
A) 50 cm
Step 2
The speed of a wave can be found using the equation

or velocity = wavelength x frequency,
then,let

replace and evaluate

so
B) 10000 cm/s
I hope this helps you
For speed you can differentiate the equation, for acceleration you can again differentiate the equation .
at t=0 the particle is slowing down , when you get equation for velocity put t=0 then only -1 is left
The complete sentence is:
In a third class lever, the distance from the effort to the fulcrum is SMALLER the distance from the load/resistance to the fulcrum.
In fact, in a third class lever, the fulcrum is on one side of the effort and the load/resistance is on the other side, so the effort is located somewhere between the two of them. This means that the distance effort-fulcrum is smaller than the distance load-fulcrum.
The AREA of the shaded region is the moving object's displacement.