Answer:
198.2m/s
Explanation:
Speed of a wave(v) is the product of the frequency of the wave (f) and its wavelength(¶).
Mathematically, v = f/¶
Given frequency of the middle C = 261.63Hz
Wavelength = 131.87cm
Converting this to meters we have;
131.87/100 = 1.32m
Speed of the sound = 261.63/1.32
Speed of the sound = 198.20m/s
Therefore the speed of sound for middle C is 198.2m/s
Answer:

Explanation:
We have,
Electric field, 
The electric dipole vector at an angle of 69.9 degrees from the direction of the field.
The torque acting on a molecule is given by :

p is electric dipole moment

So, the magnitude of the torque acting on the molecule is
.
The answer should be 1.6 kilometers.
Answer:
The 40g mass will be attached at 69 cm
Explanation:
First, make a sketch of the meterstick with the masses placed on it;
--------------------------------------------------------------------------
↓ Δ ↓
20 g.................50 cm.................40g
38 cm y cm
Apply principle of moment;
sum of clockwise moment = sum of anticlockwise moment
40y = 20 (38)
40y = 760
y = 760 / 40
y = 19 cm
Therefore, the 40g mass will be attached at 50cm + 19cm = 69 cm
12cm 50 cm 69cm
--------------------------------------------------------------------------
↓ Δ ↓
20 g.................50 cm.................40g
38 cm 19 cm