When the surface of the comb rubs on your hair, the comb is electrically charged. When the comb comes close to the paper, the charge on the comb causes charge separation on the paper bits. Since paper is neutral, positive and negative charges are equivalent. The charge on the comb charges the area of the bit of paper nearest the comb to the opposite. Thus, the bits of paper become attracted to the comb.
First, before determining which variable is which, we go over the definition of each.
The independent variable is the one which is intentionally changed in order to investigate its effect on the dependent variable.
The dependent variable is monitored and changes occur in it due to the changing conditions of the independent variable.
In this case, the location of the African violets is the independent variable as it is intentionally changed, while the rate of growth of the African violets is the dependent variable as it is being measured.
Answer:
16.77 m/s
Explanation:
Given that
Frequency of middle pitch, Fo = 261.6 Hz
Frequency of C sharp, f = 277.2 Hz
Velocity of sound in air, v = 298 m/s
Speed of sound from the source, Vs = ? m/s
Using the formula
f = Fo•(V + Vr)/(V + Vs)
← Doppler
Vr would be +ve if the receiver is moving toward source;
Vs would be -ve if source is moving toward the receiver
277.2 Hz = 261.6Hz * (298 + 0) / (298 - Vs)
277.2 = 77956.8 / (298 - Vs)
298 - Vs = 77956.8 / 277.2
298 - Vs = 281.23
Vs = 298 - 281.23
Vs = 16.77 m/s
Thus, the speed needed is 16.77 m/s
Answer:
50%
Explanation:
Efficiency = work out / work in
e = Fd / W
e = (2000 N) (2 m) / (8000 J)
e = 0.5
Let
be the direction the swimmer must swim relative to east. Then her velocity relative to the water is

The current has velocity vector (relative to the Earth)

The swimmer's resultant velocity (her velocity relative to the Earth) is then


We want the resultant vector to be pointing straight north, which means its horizontal component must be 0:

which is approximately 41º west of north.