All matter, even a cloud, has the property of electric charge. A charge imbalance causes static electricity within the cloud. At
times, the charges on a pair of clouds or on a cloud and the ground
neutralize through a discharge known as lightning.
10. During thunderstorms, positive and negative charges in clouds
become separated. Positive charge builds up on the top of
clouds, and negative charge builds up on the bottom of clouds.
How might the charged clouds affect the charges in the neutral
ground below the clouds? Describe what happens to the
charges in the ground.

16. a brave but inadequate rugby player is being pushed backward by an opposing player who is exerting a force of 800 n on him. the mass of the losing player plus equipment is 90.0 kg, and he is accelerating at 1.20m/s2 size 12{1 "." "20"" m/s" rsup { size 8{2} } } {} backward. (a) what is the force of friction between the losing player’s feet and the grass? (b) what force does the winning player exert on the ground to move forward if his mass plus equipment is 110 kg? (c) draw a sketch of the situation showing the system of interest used to solve each part. for this situation, draw a free-body diagram and write the net force equation.