A man weighing 70 kg runs alongside railroad tracks with a velocity of 18 km/h, and jumps into a car of weight 100 kg
standing on the tracks. Calculate the velocity with which the
car and man will start moving.
A.28 m/s
B. 21 m/s
C. 15 m/s
D. 32 m/s

The dipole moment of the water molecule (h2o) is 6.17x10^-30 c.m. consider a water molecule located at the origin whose dipole moment p points in the +x-direction. a chlorine ion ( of charge-1.60x10^-19c , is located at x=3.00x10^-9m . assume that is much larger than the separation d between the charges in the dipole, so that the approximate expression for the electric field along the dipole axis can be used. a) find the magnitude of the electric force that the water molecule exerts on the chlorine ion. b) what is the direction of the electric force. -x-direction or +x-direction c) is this force attractive or repulsive?