An alpha particle (a He nucleus, containing two protons and two neutrons and having a mass of 6.64×10−27 kg ) traveling horizontally at 36.6 km/s enters a uniform, vertical, 1.10 T magnetic field.

Part A What is the diameter of the path followed by this alpha particle? Express your answer in millimeters to three significant figures.

Part B What effect does the magnetic field have on the speed of the particle?

Part C What is the magnitude of the acceleration of the alpha particle while it is in the magnetic field? Express your answer in meters per second to three significant figures.

Part D What is the direction of the acceleration of the alpha particle while it is in the magnetic field?

Part E Explain why the speed of the particle does not change even though an unbalanced external force acts on it.