A railroad freight car, mass 15 000 kg, is allowed to coast along a level track at a speed of 3.0 m/s. It collides and couples with a 54 000-kg loaded second car, initially at rest and with brakes released. What percentage of the initial kinetic energy of the 15 000-kg car is preserved in the two-coupled cars after collision?
a. 78%
b. 22%
c. 18%
d. 38%
e. 14%
b
You might also like to view...
A two-dimensional object placed in the xy-plane has three forces acting on it: a force of 3.0 N along the x-axis acting at a point (3 m, 4 m);
A force of 2.0 N along the y-axis acting at (-2 m, 5 m); and a force of 5 N in the negative x direction acting at (-2 m, -3 m). What is the net torque about the point (-1 m, 1 m)? A) 7 N m counterclockwise B) 23 N m clockwise C) 3 N m counterclockwise D) 31 N m clockwise E) 7 N m clockwise
Both black and white road surfaces radiate energy. At midnight on a starry night the warmer road surface is the
A) black surface. B) white surface. C) neither, as no noticeable difference.
A constant net force acting on an object that is free to move will produce a constant
a. speed. b. velocity. c. displacement. d. acceleration. e. distance.
The Doppler shift for electromagnetic radiation from distant galaxies moving toward the observer is called a:
a. vacuum shift. c. red shift. b. blue shift. d. black shift.