9. Two spheres, one of mass 4.0 x 107 kg and the other of mass 8.0 x 107 kg are separated by a distance of 400.0 m. The force of gravity between them is
a) 1.3 N b) 530 N c) 1.8 x 104 N
d) 5.1 x 1021 N
e) 5.3 x 1022 N

An observer that stands still as the electron moves by him, will observe

22. the effect of threshold braking is to a cause skids. b. lock wheels. c. prevent locking of wheels. d. increase stopping distance.

Standing side by side ,you and a friend step off a bridge at different times and fall for 1.6s to the water below.your friend goes first,and you follow after he has dropped a distance of 2.0m.when your friend hits the water,is the seperation between the two of you 2.0m or more than 2.0m? verify your answer with a calculation.