Average speed of the runner is the rate at which the runner covers the total distance. Average speed of the runner in the race is given by,
Average speed = 
Where
Total distance = Distance covered by the runner from initial to final position
Total time = time taken by the runner to cover entire distance
Instantaneous speed is the speed of the runner at the particular moment in the given time. Instantaneous speed is given by,
Instantaneous speed = 
x = position of the runner at time t
t = time taken to cover distance x
Hence, Average speed and instantaneous speed are different for a runner running in the race.
The electric force on the electron is opposite in direction to the electric field E. E points in the -y direction, so the electric force will point in the +y direction. The magnitude of the electric force is given by:
F = Eq
F = electric force, E = electric field strength, q = electron charge
We need to set up a magnetic field such that the magnetic force on the electron balances out the electric force. Since the electric force points in the +y direction, we need the magnetic force to point in the -y direction. Using the reversed right hand rule, the magnetic field must point in the -z direction for this to happen. Since the direction is perpendicular to the +x direction of the electron's velocity, the magnetic force is given by:
F = qvB
F = magnetic force, q = charge, v = velocity, B = magnetic field strength
The electric force must equal the magnetic force.
Eq = qvB
Do some algebra to isolate B:
E = vB
B = E/v
Let's solve for the electron's velocity. Its kinetic energy is given by:
KE = 0.5mv²
KE = kinetic energy, m = mass, v = velocity
Given values:
KE = 2.9keV = 4.6×10⁻¹⁶J
m = 9.1×10⁻³¹kg
Plug in and solve for v:
4.6×10⁻¹⁶ = 0.5(9.1×10⁻³¹)v²
v = 3.2×10⁷m/s
B = E/v
Given values:
E = 7500V/m
v = 3.2×10⁷m/s
Plug in and solve for B:
B = 7500/3.2×10⁷
B = 0.00023T
B = 0.23mT
Answer:
The battery is an electric energy source, which is being used to power a motor. The motor turns this electricity into kinetic energy as it spins the fan, creates heat from friction, and creates noise as stated by the problem.
Explanation:
To me, that sounds like the "Law of Conservation of Energy".
