Definition: a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation.
Blood pressure is greater in feet because of gravity
Answer:

Downward
Explanation:
We are given that
Mass of monkey=12.8 kg
Tension=156 N
We have to find the magnitude of the elevator's minimum acceleration.

Where 
Substitute the values



Hence, the acceleration =
Direction of the elevator's minimum acceleration is downward because the elevator moves downwards.
Answer:
Length of the pipe = 53.125 cm
Explanation:
given data
harmonic frequency f1 = 800 Hz
harmonic frequency f2 = 1120 Hz
harmonic frequency f3 = 1440 Hz
solution
first we get here fundamental frequency that is express as
2F = f2 - f1 ...............1
put here value
2F = 1120 - 800
F = 160 Hz
and
Wavelength is express as
Wavelength = Speed ÷ Fundamental frequency ................2
here speed of waves in air = 340 m/s
so put here value
Wavelength =340 ÷ 160
Wavelength = 2.125 m
so
Length of the pipe will be
Length of the pipe = 0.25 × wavelength ......................3
put here value
Length of the pipe = 0.25 × 2.125
Length of the pipe = 0.53125 m
Length of the pipe = 53.125 cm