A20-kg barrel is rolled up a 20-m ramp to the back of a truck whose floor is 5.0 m above the ground. what work is done in loading one barrel into the truck? a: 980j b: 19,600j c : 4900j d : imposible to tell because velocity is not given.,

Why does lightning travel from clouds to the ground? a. the negatively charged ground attracts the positive charge from the clouds b. charges are exchanged between negatively charged clouds and positively charged ground c. gravity pulls the negatively charged energy from clouds downward d. gravity pulls the positively charged energy from clouds downward