Answer:
0.25 m
Explanation:
v = Speed of sound in air at 20°C = 343 m/s
f = Frequency = 686 Hz
Wavelength is given by
The wavelength is 0.5 m
Path difference for destructive interference
The required distance is 0.25 m
Answer:
b
Explanation:
because the same current flows through the lamps and the total voltage across all the lamps is the sum of all the separate voltages across them.
Answer:
490 N
Explanation:
The elevator is rising at constant velocity: this means the acceleration of the system is zero, so according to Newton's second law, the net force on the system is also zero:
There are two forces acting on the person standing on the scale:
- its weight, downward, whose magnitude is W=490 N
- The normal force of the scale on the person, N, which is upward
Since the net force must be zero, we have:
From which we find the normal force:
180 - (40 * 2) = 100°
So the answer is (D) 100°
Hope this helps! :)