Answer:
17.15 m/s
Explanation:
Parameters given:
Magnetic field, B = 0.8 T
Mass of ball, m = 0.007 kg
Charge of ball, q = 0.005 C
The magnetic force acting on the charged ball due to the magnetic field is given as:
F = qvBsinθ
where v = velocity of the ball and θ = angle between the horizontal and the magnetic field = 90°
The force of the ball will be in the opposite direction but of equal magnitude:
= -qvBsin(90) = -qvB
To cancel out the effect of gravity, the magnetic force must be equal to the gravitational force acting on the ball:
F = mg
Therefore:
mg = -qvB
Solving for velocity, v, we have:
v = 17.15 m/s
The ball must be moving at a velocity of 17.15 m/s.
In order to calculate the thermal energy, first let's calculate the power, using the formula:
For a voltage V = 9 Volts and a resistance R = 50 ohms, we have:
Now, multiplying the power by the time (in seconds), we can find the energy:
In scientific notation, we have an energy of 7.3 * 10^2 J, therefore the correct option is the fourth one.