The initial kinetic energy of the boat and its rider is

After Sam stops it, the final kinetic energy of the boat+rider is

because its final velocity is zero.
For the law of conservation of energy, the work done by Sam is the variation of kinetic energy of the system:

where the negative sign is due to the fact that the force Sam is applying goes against the direction of motion of the boat.
Answer:
4.4×10⁻⁷ Coulomb
Explanation:
V = Voltage = 5.8 kV
d = Potential distance = 2.8 mm = 0.0028 m
A = Area = 0.3×0.08 = 0.024 m²
ε₀ = permittivity constant in a Vacuum= 8.85×10⁻¹² F/m

Magnitude of charge transferred between a carpet and a shoe is 4.4×10⁻⁷ Coulomb.
A wave is characterized by the cyclic occurrences of crests and troughs. Wavelengthis defined as the distance between two consecutive troughs or two crests and the Frequency is defined as the number of cycles that pass through a point per second