Velma is in a train headed north past Mort at 30 m/s. Velma has a slingshot that can shoot pebbles at 40 m/s. Velma shoots a pebble toward the rear of the train. Mort observes the pebble's velocity to be
A) 70 m/s north.
B) 70 m/s south.
C) 40 m/s south.
D) 10 m/s south.
E) 10 m/s north.
D
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The fact that the properties of the Universe are close to the dividing line between open and closed Universes refers to the _______________ problem
Fill in the blank(s) with correct word
Physical Pendulum: A simple pendulum that consists of a small ball of mass m and a massless wire of length L swings with a period T. Suppose now that the mass is rearranged so that mass of the ball was reduced but the mass of the wire was increased, with the total mass remaining m and the length being L. What is true about the new period of swing? (There could be more than one correct choice.)
A. The new period is T because the total mass m has not changed. B. The new period is T because the length L has not changed. C. The new period is greater than T. D. The new period is less than T. E. The new period is T because neither L nor m have changed.
The Complementary color of BLUE light is:
a. Magenta b. Yellow c. Cyan d. White
Two hoops or rings (I = MR2) are centered, lying on a turntable. The smaller ring has radius = 0.05 m; the larger has radius = 0.10 m. Both have a mass of 5.0 kg. What is the total moment of inertia as the turntable spins? Ignore the mass of the turntable
a. 7.5E–1 kg·m2 b. 1.1E–1 kg·m2 c. 1.3E–2 kg·m2 d. 6.3E–2 kg·m2 e. 5.0E–2 kg·m2