When can we be certain that the average velocity of an object is always equal to its instantaneous velocity?
A) always
B) never
C) only when the velocity is constant
D) only when the acceleration is constant
E) only when the acceleration is changing at a constant rate
Answer: C
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Answer the following questions for projectile motion on level ground assuming negligible air resistance (the initial angle being neither 0º nor 90º: (a) Is the acceleration ever zero? (b) Is the acceleration ever in the same direction as a component of velocity? (c) Is the acceleration ever opposite in direction to a component of velocity?
A. (a) No, (b) No, when the projectile is coming down, (c) No, on way up, because the acceleration is always downward throughout the satellite trip. B. (a) No, (b) Yes, when the projectile is coming down, (c) Yes, on way up, because the acceleration is always downward throughout the satellite trip. C. (a) Yes, (b) No, when the projectile is coming down, (c) Yes, on way up, because the acceleration is always downward throughout the satellite trip.
An object weighing 44.1 N hangs from a vertical massless ideal spring. When set in vertical motion, the object obeys the equation y(t) = (6.20 cm) cos[(2.74 rad/s)t - 1.40]
(a) Find the time for this object to vibrate one complete cycle. (b) What are the maximum speed and maximum acceleration of the object. (c) What is the TOTAL distance the object moves through in one cycle. (d) Find the maximum kinetic energy of the object. (e) What is the spring constant of the spring.
Faraday's law describes
A) electromagnetic induction. B) the connection between current, voltage, and resistance. C) the attraction and repulsion of magnetic poles. D) the force between magnetic poles. E) all of the above
Two masses, MA and MB, with MB = 2MA, are released at the same time and allowed to fall straight down. Neglect air resistance. When we compare their kinetic energies after they have fallen for equal times, we find that
a. KB = KA. b. KB = 2KA. c. KB = 4KA. d. KA = 2KB. e. KA = 4KB.