Ideally (no friction), should this number be equal to one, i. e., should the potential energy change be equal to the work done? Yes
or
No

Which of the following represents an upside-down image?

When you drop a pebble from height a it reaches the ground with speed v if there is no air resistance. from what height should you drop it so it will reach the ground with three times the speed? (a) 9m (b) 3m (c) 6m (d) 18m

Several mountains together form a mountain . a few of these combined form a mountain system. several systems combined form a mountain , which can stretch thousands of miles in length.