A railroad car collides with and sticks to an identical railroad car that is initially at rest. After the collision, the kinetic energy of the system
A) is the same as before.
B) is half as much as before.
C) is one third as much as before.
D) is one fourth as much as before.
E) is one quarter as much as before.
B
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A spring-powered dart gun is un-stretched and has a spring constant 12.0 N/m. The spring is compressed by 8.00 cm and a 5.00 gram projectile is placed in the gun. The velocity of the projectile when it is shot from the gun is
A. 1.52 m/s. B. 2.54 m/s. C. 3.92 m/s. D. 4.24 m/s. E. 5.02 m/s.
Resistor A has twice the resistance of resistor B. When individually connected across a given potential difference, which one dissipates the most power; and when connected in series across the same potential difference, which one dissipates the most power?
a. A, A b. A, B c. B, B d. B, A
The strong force is the force that
a. binds electrons to the nucleus in an atom. b. holds the moon in orbit around Earth. c. creates the magnetic field associated with sunspots. d. produces the extremely high temperatures in the solar corona. e. binds protons and neutrons together to form a nucleus.
Three point charges, two positive and one negative, each having a magnitude of 20 ?C are placed at the vertices of an equilateral triangle (30 cm on a side). What is the magnitude of the electrostatic force on one of the positive charges?
a. 69 N b. 40 N c. 80 N d. 57 N e. 20 N