1. Many Solids are made of crystals like salt, sugar or quartz. Briefly describe the arrangement of atoms in crystals compared to non-
crystalline solids or amorphous solids like rubber or plastics.

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.

70 give a real life example showing how sensory neurons work with the motor neurons

If a car is traveling on the highway at a constant velocity, the force that pushes the car forward must be a. equal to the weight of the car. b. less than the force of friction exerted upon the car. c. equal to the force of friction exerted upon the car. d. greater than the weight of the car.