A26.0 kg child plays on a swing having support ropes that are 2.40 m long. a friend pulls her back until the ropes are 45.0 ∘ from the vertical and releases her from rest. what is the potential energy for the child just as she is released, compared with the potential energy at the bottom of the swing? how fast will she be moving at the bottom of the swing? how much work does the tension in the ropes do as the child swings from the initial position to the bottom?

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?