Velma is in a train moving eastward at 70 m/s. She throws a ball toward the rear of the train, throwing it at her normal "throwing speed" of 20 m/s. The ball's velocity relative to Mort, who is standing beside the tracks, is
A) 50 m/s westward.
B) 90 m/s eastward.
C) 20 m/s eastward.
D) 50 m/s eastward.
E) 20 m/s westward.
D
You might also like to view...
What is the lowest pressure indicated by an isobar on Fig. 48.3?
Riding down a river in an old canoe, if the discharge of the river increases a little and the width and the depth of the river stay the same, the speed of the river will
A) decrease. B) increase. C) stay the same. D) become unpredictable.
Acceleration: Under what condition is average velocity equal to the average of the object's initial and final velocity?
A. This can only occur if there is no acceleration. B. The acceleration is constant. C. This can occur only when the velocity is zero. D. The acceleration must be constantly increasing. E. The acceleration must be constantly decreasing.
Coulomb's Law: Three identical 3.0-µC charges are placed at the vertices of an equilateral triangle that measures 30 cm on a side. What is the magnitude of the electrostatic force on any one of the charges? (k = 1/4??0 = 9.0 × 109 N ? m2/C2)
A. 1.6 N B. 1.8 N C. 2.0 N D. 2.2 N E. 2.4 N