A 5.0-kg mass is suspended by a string from the ceiling of an elevator that is moving upward with a speed which is decreasing at a constant rate of 2.0 m/s in each second. What is the tension in the string supporting the mass?
A. 49 N
B. 39 N
C. 59 N
D. 10 N
E. 42 N
Answer: B
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A planet of constant mass orbits the sun in an elliptical orbit. Neglecting any friction effects, what happens to the planet's rotational kinetic energy about the sun's center?
A) It decreases continually. B) It increases continually. C) It remains constant. D) It increases when the planet approaches the sun, and decreases when it moves farther away. E) It decreases when the planet approaches the sun, and increases when it moves farther away.
The energy difference between the upper and lower levels in a certain laser is 1.9593 eV. What is the wavelength of the light emitted by the laser?
The figure below shows a planet traveling in a clockwise direction on an elliptical path around a star located at one focus of the ellipse. When the planet is at point A,
a.
its speed is constant.
b.
its speed is increasing.
c.
its speed is decreasing.
d.
its speed is a maximum.
e.
its speed is a minimum.
A parallel-plate capacitor , made of two circular plates of radius R = 10 cm, is being charged
What is the magnitude of the induced magnetic field induced by the displacement current between the plates of the capacitor at a distance r = 2 cm from the axis of the plates at a time when the electric field varies at the rate dE/dt = 2 × 1012 V/m s? A) 0.7 × 10-7 T B) 2.2 × 10-7 T C) 8.1 × 10-7 T D) 3.5 × 10-7 T E) 1.3 × 10-7 T