Answer:
There are three basic categories of musical instruments: percussion, wind, and stringed instruments. Most musical instruments use resonance to amplify sound waves and make sounds louder. In a musical instrument, the whole instrument and the air inside it may vibrate when the head of the drum is struck.
I assume the 100 N force is a pulling force directed up the incline.
The net forces on the block acting parallel and perpendicular to the incline are
∑ F[para] = 100 N - F[friction] = 0
∑ F[perp] = F[normal] - mg cos(30°) = 0
The friction in this case is the maximum static friction - the block is held at rest by static friction, and a minimum 100 N force is required to get the block to start sliding up the incline.
Then
F[friction] = 100 N
F[normal] = mg cos(30°) = (10 kg) (9.8 m/s²) cos(30°) ≈ 84.9 N
If µ is the coefficient of static friction, then
F[friction] = µ F[normal]
⇒ µ = (100 N) / (84.9 N) ≈ 1.2
In a stationary situation, the weight of person is
This is the weight "felt" by the scale, which is basically the normal reaction applied by the scale on the person, and which uses the value of g (9.81) as reference to convert the weight (602.8 N) into a mass (62 kg).
When the person is in the elevator, the scale says 77 kg. The scale is still using the same value of conversion (9.81), so the apparent weight "felt" by the scale is
This is the normal reaction applied by the scale on the person, and which is directed upward. Besides this force, there is still the weight W of the person, acting downward. So, if we use Newton's second law:
where a is the acceleration of the elevator. If we solve for a, we find
The negative sign means the acceleration is in the opposite direction of g (which we take positive), so it means the elevator is going upward.
<span>the speed of something in a given direction. so i think none of these</span>