The moment of a couple is Force × perpendicular distance from the arm of the line of action
so the arm of the couple= moment of couple/force=8.5/34=0.25m
the arm is 0.25m
Here's what you need to know about waves:
Wavelength = (speed) / (frequency)
Now ... The question gives you the speed and the frequency,
but they're stated in unusual ways, with complicated numbers.
Frequency: How many each second ?
The thing that's making the waves is vibrating 47 times in 26.9 seconds.
Frequency = (47) / (46.9 s) = 1.747... per second. (1.747... Hz)
Speed: How far a point on a wave travels in 1 second.
The crest of one wave travels 4.16 meters in 13.7 seconds.
Speed = (4.16 m / 13.7 sec) = 0.304... m/s
Wavelength = (speed) / (frequency)
Wavelength = (0.304 m/s) / (1.747 Hz) = 0.174 meter per second
C. Light sometimes behaves like waves and at other times like particles.
The 3rd one. The question can be tested by a systematic procedure
Yes. If your smartphone was floating in front of your face, motionless
relative to you, it would require a force to start it moving toward you or
away from you.
But there's no minimum force required. ANY force, no matter how small,
even smaller than the smallest force that you can imagine, would set it in
motion.
The thing is, though, that the smaller the force acting on it, the smaller
acceleration it would get, and the slower it would move away from where
it is.
So if, say, you wanted to send it across the crew compartment and over
to your sleeping bag on the wall, and you had all day to watch it mope
along over there, you might breathe on it, and the force of your breath
would set it in slow motion in that direction. But if you wanted to throw it
at your crewmate, you'd need to give it more force.
