An electron moving perpendicular to a uniform magnetic field of 3.2 × 10-2 T moves in a circle of radius 0.40 cm. How fast is this electron moving? (mel = 9.11 × 10-31 kg. e = 1.60 × 10-19 C)
A) 2.2 × 107 m/s
B) 1.9 × 10-2 m/s
C) 1.9 × 10-30 m/s
D) 3.0 × 106 m/s
E) 8.0 × 106 m/s
A
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Thermal Expansion: The coefficient of linear expansion of copper is 17 × 10-6 K-1 and that of steel is 12 × 10-6 K-1. At 12°C a steel rod has a diameter of 2.540 cm and a copper pipe has a diameter of 2.536 cm. Which one of the following quantities is closest to the temperature to which the copper pipe must be heated in order for the unheated steel rod to fit snugly in the copper pipe?
A. 53°C B. 81°C C. 93°C D. 105°C E. 143°C
The magnetic force on a charged particle moving at a constant speed in a uniform magnetic field will be doubled when the angle between the velocity of the particle and the direction of the magnetic field changes from 25.0° to
a. 57.7°. b. 12.5°. c. 12.2°. d. 50.0°.
A speed of 60 mi/h is closest to which of the following? (2.54 cm = 1.00 in.)
A) 60 m/s B) 20 m/s C) 30 km/h D) 120 m/s E) 30 m/s
The hottest star is the one that glows
A) red. B) white. C) blue. D) need more information