Ascientific model can be used to

a. replace study of the actual system
b. better understand systems and processes
c. complicate ideas
d. all of the above

In which of the following is positive work done by a person on a suitcase

Name two kinds of practical electric pumps.

During a medieval siege of a castle, the attacking army uses a trebuchet to hurl heavy stones at the castle walls. if the trebuchet launches the stones with a velocity of at an angle of 50.0°, (a) how long does it take the stone to hit the ground? (b) what is the maximum distance that the trebuchet can be from the castle wall to be in range? (c) how high will the stones go? show all your work.